Fc Region Of Human Immunoglobulin Research Articles

A SARS-CoV-2 NSP7 homolog of a Treg epitope suppresses CD4+ and CD8+ T cell memory responses.

Pathogens escape host defenses by T-cell epitope mutation or deletion (immune escape) and by simulating the appearance of human T cell epitopes (immune camouflage). We identified a highly conserved, human-like T cell epitope in non-structural protein 7 (NSP7) of SARS-CoV-2, RNA-dependent RNA polymerase (RdRp) hetero-tetramer complex. Remarkably, this T cell epitope has significant homology to a T regulatory cell epitope (Tregitope) previously identified in the Fc region of human immunoglobulin G (IgG) (Tregitope 289). We hypothesized that the SARS-CoV-2 NSP7 epitope (NSP7-289) may induce suppressive responses by engaging and activating pre-existing regulatory T cells. We therefore compared NSP7-289 and IgG Tregitopes (289 and 289z, a shorter version of 289 that isolates the shared NSP7 epitope) in vitro. Tregitope peptides 289, 289z and NSP7-289 bound to multiple HLA-DRB1 alleles in vitro and suppressed CD4+ and CD8+ T cell memory responses. Identification and in vitro validation of SARS-CoV-2 NSP7-289 provides further evidence of immune camouflage and suggests that pathogens can use human-like epitopes to evade immune response and potentially enhance host tolerance. Further exploration of the role of cross-conserved Tregs in human immune responses to pathogens such as SARS-CoV-2 is warranted.

A phase 1 study of ALX148, a CD47 blocker, alone and in combination with established anticancer antibodies in patients with advanced malignancy and non-Hodgkin lymphoma.

3068 Background: CD47, a marker of self, is a myeloid checkpoint that is upregulated by tumor cells to evade the host’s immune response. ALX148 is a fusion protein comprised of an engineered high affinity CD47 binding domain of SIRPα genetically linked to an inactive Fc region of human immunoglobulin. We have previously shown ALX148 blocks CD47 and safely enhances the activity of targeted anticancer antibodies and checkpoint inhibitors through Fc dependent and independent mechanisms in nonclinical models (ASH 2017 #112). Methods: As of Feb 07, 2018, 30 patients (pts) were enrolled to escalating dose cohorts of ALX148 (0.3 mg/kg [mpk] IV every week [QW] - 30 mpk every other week [QoW]) as a single agent (Part 1) or in combination with standard regimens of pembrolizumab (P), trastuzumab (T), or rituximab (R) (Part2). The primary endpoint for each Part is first cycle dose limiting toxicity (DLT). Tumor response, pharmacokinetics (PK), and CD47 target occupancy (TO) are also characterized. Results: Part 1 results are summarized. 25 pts received single agent ALX148. 22 pts experienced any AE. Maximum CTCAE treatment related AEs that occurred in > 1 pt were Dizziness 2G1; Fatigue 3G1; Headache 4G1; Rash 1G1,1G2; and Thrombocytopenia 2G3. Two pts experienced a DLT (Neutropenia with infection, 3mpk; Thrombocytopenia with significant bleed, 30 mpk). There were 4 pts who reported ≥G3 AE (Infection 1G3, 3mpk; Pancreatitis 1G3, 30 mpk; Thrombocytopenia 1G3, 3 mpk and 1G3, 30 mpk; Neutropenia 1G4, 3mpk) and 1G5 Death (30mpk; etiology being investigated). No single agent MTD was identified, and the maximum administered dose (MAD) was 30 mpk QoW. Four pts achieved stable disease including 1 pt with NSCLC who had a 15% tumor reduction. ALX148 demonstrated linear PK at doses ≥ 10 mpk QW and full TO at doses ≥ 3 mpk QW. To date, 5 Part 2 pts received ALX148 (10 mpk QW) in combination (3 with P; 1 with T; 1 with R). Conclusions: ALX148 is generally well tolerated in pts with advanced tumors with favorable PK/TO characteristics at doses evaluated. The MAD of single agent ALX148 is 30 mpk QoW. Accrual to the Part 2 combination cohorts is ongoing. Clinical trial information: NCT03013218.

249. Preliminary Results of a Phase 1, Open-Label, Safety and Tolerability Study of a Single Intravitreal Injection of AAV2-sFLT01 in Patients with Neovascular Age-Related Macular Degeneration

Clinical Trial: www.clinicaltrials.gov NCT01024998Introduction: Vascular endothelial growth factor (VEGF) plays a critical role in the development of the neovascular AMD (wet AMD), the most common cause of new onset blindness in elderly adults. While intravitreal (IVT) administration of anti-VEGF agents are effective for improving vision in wet AMD patients, the need for repeated monthly IVT injections imposes a burden on patients and ophthalmologists which may limit the realization of the full benefits of VEGF inhibition. AAV2-sFLT01 is a replication defective, recombinant adeno-associated virus (serotype 2) vector (AAV2) that encodes sFLT01, a novel soluble chimeric protein composed of domain 2 of VEGF receptor 1 and the Fc region of human Immunoglobulin G type 1 (IgG1). We investigated the safety and tolerability of a single IVT administration of AAV2-sFLT01 in wet AMD patients. Methods: The study was a Phase 1, open-label,, dose-escalating, safety and tolerability study conducted in 4 sites in the USA. 5 cohorts of patients with BCVA of ≤20/100 in the study eye received a single IVT injection of one of four AAV2-sFLT01 doses (2×108, 2×109, 6×109, or 2×1010 vg). Patients in cohorts 1-4 had subfoveal disciform scarring, while cohort 5 patients had responsiveness to an anti-VEGF therapy within 12 months prior to enrollment. All patients were monitored for 52 weeks following the injection in the core study, and encouraged to participate in the extended follow-up program for up to 4 years. The primary safety endpoint was the occurrence of adverse events. Biological activity was evaluated by changes from baseline in sub/intraretinal fluid by optical coherence tomography (OCT), best corrected visual acuity (BCVA) and sFLT01 protein level detected in the aqueous fluid. Results: 19 patients with end-stage/advanced wet AMD (53% males, median age 77.0 years, median time since diagnosis of AMD of 5.4 years and median basal BCVA of 22.0 letters) were treated. All patients completed the 52-week study with 17 patients consenting to the 4 year extended follow-up study. Overall, the treatment was considered safe and tolerable with no dose-limiting toxicity observed in any dose level. 11/19 patients were expected to show an anti-VEGF response clinically. Of them, transient (2 patients) and sustained (4 patients) reduction in retinal thickness suggested a biological effect of the treatment. Aqueous sFLT01 protein expression was identified in 5 patients receiving 2×1010 vg. Post-treatment changes in BCVA did not correlate with other parameters of biological activity. Conclusion: Despite advanced disease state, a sustained reduction in retinal fluid in four patients provides evidence of biological activity supporting the concept that a sustained therapeutic anti-VEGF level can be achieved following a single intravitreal administration of an ocular gene therapy.

IBI302, a promising candidate for AMD treatment, targeting both the VEGF and complement system with high binding affinity in vitro and effective targeting of the ocular tissue in healthy rhesus monkeys

Uncontrolled activation of complement and upregulation of vascular endothelial growth factor (VEGF) play fundamental roles in age-related macular degeneration (AMD). However, most drugs used to treat AMD focus on a single target, and the percentage of effectively treated patients in clinical practice needs to be improved. Therefore, novel AMD treatment approaches are needed. IBI302 is a novel bispecific decoy receptor fusion protein designed with both a VEGF inhibition domain and a complement cascade inhibition domain, which are connected by the Fc region of human immunoglobulin. In this study, we systematically evaluated the binding affinity between IBI302 and VEGF isoforms and complement proteins by using surface plasmon resonance (SPR) technology. Anti-VEGF blockers (aflibercept and bevacizumab) and complement receptor 1 were used as references. The SPR assay results indicated that IBI302 could bind different VEGF isoforms and complement proteins with high affinity. The biological activity of IBI302 was also studied. IBI302 showed an inhibitory effect on human primary umbilical vein endothelial cell proliferation and the activation of complement pathways in vitro. Finally, the pharmacokinetic (PK) properties of IBI302 were evaluated in rhesus monkeys. The PK results showed that after a 0.5 mg/eye intravitreal dosage, IBI302 became rapidly distributed from the vitreous humor into targeted tissues and remained active over 504 h. Overall, the favorable anti-angiogenic and anti-complement effects of IBI302 along with the good PK profiles in rhesus monkeys support the selection and development of IBI302 as a promising candidate for AMD treatment.

Mutated Leguminous Lectin Containing a Heparin-Binding like Motif in a Carbohydrate-Binding Loop Specifically Binds to Heparin.

We previously introduced random mutations in the sugar-binding loops of a leguminous lectin and screened the resulting mutated lectins for novel specificities using cell surface display. Screening of a mutated peanut agglutinin (PNA), revealed a mutated PNA with a distinct preference for heparin. Glycan microarray analyses using the mutated lectin fused to the Fc region of human immunoglobulin, revealed that a particular sulfated glycosaminoglycan (GAG), heparin, had the highest binding affinity for mutated PNA among 97 glycans tested, although wild-type PNA showed affinity towards Galβ1-3GalNAc and similar galactosylated glycans. Further analyses of binding specificity using an enzyme-linked immunoadsorbent assay demonstrated that the mutated PNA specifically binds to heparin, and weakly to de-2-O-sulfated heparin, but not to other GAG chains including de-6-O-sulfated and de-N-sulfated heparins. The mutated PNA had six amino acid substitutions within the eight amino acid-long sugar-binding loop. In this loop, the heparin-binding like motif comprised three arginine residues at positions 124, 128, and 129, and a histidine at position 125 was present. Substitution of each arginine or histidine residue to alanine reduced heparin-binding ability, indicating that all of these basic amino acid residues contributed to heparin binding. Inhibition assay demonstrated that heparin and dextran sulfate strongly inhibited mutated PNA binding to heparin in dose-dependent manner. The mutated PNA could distinguish between CHO cells and proteoglycan-deficient mutant cells. This is the first report establishing a novel leguminous lectin that preferentially binds to highly sulfated heparin and may provide novel GAG-binding probes to distinguish between heterogeneous GAG repeating units.

Adaptive Assembly: Maximizing the Potential of a Given Functional Peptide with a Tailor-Made Protein Scaffold

Protein engineering that exploits known functional peptides holds great promise for generating novel functional proteins. Here we propose a combinatorial approach, termed adaptive assembly, which provides a tailor-made protein scaffold for a given functional peptide. A combinatorial library was designed to create a tailor-made scaffold, which was generated from β hairpins derived from a 10-residue minimal protein "chignolin" and randomized amino acid sequences. We applied adaptive assembly to a peptide with low affinity for the Fc region of human immunoglobulin G, generating a 54-residue protein AF.p17 with a 40,600-fold enhanced affinity. The crystal structure of AF.p17 complexed with the Fc region revealed that the scaffold fixed the active conformation with a unique structure composed of a short α helix, β hairpins, and a loop-like structure. Adaptive assembly can take full advantage of known peptides as assets for generating novel functional proteins.

Improving the anti-toxin abilities of the CMG2-Fc fusion protein with the aid of computational design.

CMG2-Fc is a fusion protein composed of the extracellular domain of capillary morphogenesis protein 2 (CMG2) and the Fc region of human immunoglobulin G; CMG2-Fc neutralizes anthrax toxin and offers protection against Bacillus anthracis challenge. To enhance the efficacy of CMG2-Fc against anthrax toxin, we attempted to engineer a CMG2-Fc with an improved affinity for PA. Using the automatic design algorithm FoldX and visual inspection, we devised two CMG2-Fc variants that introduce mutations in the CMG2 binding interface and improve the computationally assessed binding affinity for PA. An experimental affinity assay revealed that the two variants showed increased binding affinity, and in vitro and in vivo toxin neutralization testing indicated that one of these mutants (CMG2-Fc(E117Q)) has superior activity against anthrax toxin and was suitable for further development as a therapeutic agent for anthrax infections. This study shows that the computational design of the PA binding interface of CMG2 to obtain CMG2-Fc variants with improving anti-toxin abilities is viable. Our results demonstrate that computational design can be further applied to generate other CMG2-Fc mutants with greatly improved therapeutic efficacy.

Novel VEGF Decoy Receptor Fusion Protein Conbercept Targeting Multiple VEGF Isoforms Provide Remarkable Anti-Angiogenesis Effect In Vivo

VEGF family factors are known to be the principal stimulators of abnormal angiogenesis, which play a fundamental role in tumor and various ocular diseases. Inhibition of VEGF is widely applied in antiangiogenic therapy. Conbercept is a novel decoy receptor protein constructed by fusing VEGF receptor 1 and VEGF receptor 2 extracellular domains with the Fc region of human immunoglobulin. In this study, we systematically evaluated the binding affinity of conbercept with VEGF isoforms and PlGF by using anti-VEGF antibody (Avastin) as reference. BIACORE and ELISA assay results indicated that conbercept could bind different VEGF-A isoforms with higher affinity than reference. Furthermore, conbercept could also bind VEGF-B and PlGF, whereas Avastin showed no binding. Oxygen-induced retinopathy model showed that conbercept could inhibit the formation of neovasularizations. In tumor-bearing nude mice, conbercept could also suppress tumor growth very effectively in vivo. Overall, our study have demonstrated that conbercept could bind with high affinity to multiple VEGF isoforms and consequently provide remarkable anti-angiogenic effect, suggesting the possibility to treat angiogenesis-related diseases such as cancer and wet AMD etc.

A universal surrogate peptide to enable LC‐MS/MS bioanalysis of a diversity of human monoclonal antibody and human Fc‐fusion protein drug candidates in pre‐clinical animal studies

For the development of human antibody Fc (fraction crystallizable) region-containing therapeutic protein candidates, which can be either monoclonal antibodies (mAbs) or pharmacologically active proteins/peptides fused to the Fc region of human Immunoglobulin G (IgG), reliable quantification of these proteins in animal pharmacokinetic study plasma samples is critical. LC-MS/MS has emerged as a promising assay platform for this purpose. LC-MS/MS assays used for bioanalysis of human antibody Fc region-containing therapeutic protein candidates frequently rely upon quantification of a 'signature' surrogate peptide whose sequence is unique to the protein analyte of interest. One drawback of the signature peptide approach is that a new LC-MS/MS assay must be developed for each new human Fc region-containing therapeutic protein. To address this issue, we propose an alternative 'universal surrogate peptide' approach for the quantification of human antibody Fc region-containing therapeutic protein candidates in plasma samples from all nonclinical species. A single surrogate tryptic peptide was identified in the Fc region of most human antibody Fc-containing therapeutic protein candidates. An LC-MS-MS method based upon this peptide was shown to be capable of supporting bioanalysis of a diversity of human Fc region-containing therapeutic protein candidates in plasma samples of all commonly used animal species.

Soluble Vascular Endothelial Growth Factor Decoy Receptor FP3 Exerts Potent Antiangiogenic Effects

The binding of vascular endothelial growth factor (VEGF) to its receptors stimulates tumor growth; therefore, modulation of VEGF would be a viable approach for antiangiogenic therapy. We constructed a series of soluble decoy receptors containing different VEGF receptor 1 (FLT1) and VEGF receptor 2 (KDR) extracellular domains fused with the Fc region of human immunoglobulin (Ig) and evaluated their antiangiogenic effects and antitumor effects. Results of in vitro binding and cell proliferation assays revealed that decoy receptor FP3 had the highest affinity to VEGF-A and -B. Compared with bevacizumab, FP3 more effectively inhibited human umbilical vein endothelial cell (HUVEC) migration and vessel sprouting from rat aortic rings. FP3 significantly reduced phosphorylation of AKT and ERK1/2, critical proteins in the VEGF-mediated survival pathway in endothelial cells. Moreover, FP3 inhibited tumor growth in human hepatocellular carcinoma (HepG2), breast cancer (MCF-7), and colorectal cancer (LoVo) tumor models, and reduced microvessel density in tumor tissues. The FP3-mediated inhibition of tumor growth was significantly higher than that of bevacizumab at the same dose. FP3 also demonstrated synergistic antitumor effects when combined with 5-fluorouracil (5-FU). Taken together, FP3 shows a high affinity for VEGF and produced antiangiogenic effects, suggesting its potential for treating angiogenesis-related diseases such as cancer.

Transient Co-Expression of Post-Transcriptional Gene Silencing Suppressors for Increased in Planta Expression of a Recombinant Anthrax Receptor Fusion Protein

Potential epidemics of infectious diseases and the constant threat of bioterrorism demand rapid, scalable, and cost-efficient manufacturing of therapeutic proteins. Molecular farming of tobacco plants provides an alternative for the recombinant production of therapeutics. We have developed a transient production platform that uses Agrobacterium infiltration of Nicotiana benthamiana plants to express a novel anthrax receptor decoy protein (immunoadhesin), CMG2-Fc. This chimeric fusion protein, designed to protect against the deadly anthrax toxins, is composed of the von Willebrand factor A (VWA) domain of human capillary morphogenesis 2 (CMG2), an effective anthrax toxin receptor, and the Fc region of human immunoglobulin G (IgG). We evaluated, in N. benthamiana intact plants and detached leaves, the expression of CMG2-Fc under the control of the constitutive CaMV 35S promoter, and the co-expression of CMG2-Fc with nine different viral suppressors of post-transcriptional gene silencing (PTGS): p1, p10, p19, p21, p24, p25, p38, 2b, and HCPro. Overall, transient CMG2-Fc expression was higher on intact plants than detached leaves. Maximum expression was observed with p1 co-expression at 3.5 days post-infiltration (DPI), with a level of 0.56 g CMG2-Fc per kg of leaf fresh weight and 1.5% of the total soluble protein, a ten-fold increase in expression when compared to absence of suppression. Co-expression with the p25 PTGS suppressor also significantly increased the CMG2-Fc expression level after just 3.5 DPI.

A variant human IgG1-Fc mediates improved ADCC

Ribosome display was applied to the Fc region of human immunoglobulin G (IgG1) to select for improved binding to human FcγRIIIa, the receptor expressed on human natural killer cells that mediates antibody-dependent cellular cytotoxicity (ADCC). A library of human Fcγ1 variants was generated using error-prone polymerase chain reaction, and subjected to multiple rounds of ribosome display selection against progressively decreasing concentrations of soluble human FcγRIIIa, to enrich for improved binders. Radioimmunoassay and alphascreen analyses of the aglycosylated IgG-Fc output revealed variants with improved binding to FcγRIIIa relative to wild-type IgG-Fc. Subsequent expression in human (HEK-EBNA) cells generated glycosylated IgGs with modified activity in ADCC assays. One particular variant, 125_B01 triggered enhanced ADCC (EC(50) up to four-fold reduced with increased maximal lysis) relative to wild-type antibody, having more equal levels of ADCC for each allotype (V158/F158) of FcγRIIIa. Deconvolution of individual replacements within the variant showed that improved function arose from the Phe243Leu replacement within the CH2 domain, rather than the CH3 domain replacements Thr393Ala or His433Pro. Surprisingly, the oligosaccharide profiles of 125_B01 indicated more oligosaccharide chains lacking fucose, or with bisecting N-acetylglucosamine relative to wild-type IgG1, which correlates with improved function and the replacement Phe243Leu that is a carbohydrate contact residue within the C(H)2 domain.

Abstract LB-382: Inhibition of CD95 signalling by APG-101 enhances efficacy of radiotherapy (RT) and reduces RT-induced tumor satellite formation

Abstract CD95 is a prototype death receptor that regulates the induction of apoptosis, upon binding of its ligand CD95L. Therefore, activation of the CD95L/CD95 system has been regarded an excellent target for treatment of various malignancies. In contrast to the aim of promoting CD95 activation, there is compelling evidence that CD95 is able to promote tumor growth through intracellular non-apoptotic signalling mechanisms. This mechanism has recently been described for glioblastoma, in which activation of CD95 by CD95L leads to invasive growth and glioma cell migration. This is signalled through increased activity of pivotal glioblastoma invasion-related proteases, that is matrix metalloproteinases (MMP). With this shift of paradigms, blocking of the CD95L mediated invasion of tumor cells and subsequent tumor progression may therefore be a promising approach in anti-glioma therapy. APG101 is a fusion protein, consisting of the extracellular domain of human CD95 and the Fc-region of human immunoglobulin G. Hence, it acts as a soluble CD95 receptor trapping the CD95 ligand. The presented project aims at analyzing the clinical relevance of blocking CD95 signalling, given the fact that glioma patients with upregulated CD95 expression have worse survival rates than those with intermediate expression levels. In proof-of principle experiments APG101 inhibits CD95L-mediated invasion of glioma cells. More importantly, APG101-treatment (100 mg/kg body weight) resulted in significantly prolonged survival of SMA560-tumor bearing Vm/Dk mice, less glioma cell satellites in the surrounding tissue and reduced activity of MMP. APG101 in combination with focal irradiation at 6 Gy demonstrated a remarkable reduction of tumor growth with a significantly prolonged survival compared with irradiation treatment alone and inhibition of the proinvasive properties of radiotherapy as demonstrated by magnetic resonance imaging and histology. Surprisingly, APG-101 added to the vascular endothelial growth factor receptor (VEGFR) inhibitor cediranib (AZD2171) did not increase the survival of SMA-560-tumor bearing mice as compared to cediranib alone nor did it impair the proinvasive consequences of cediranib. Our data strongly support the potential use and clinical evaluation of APG101 in combination with radiotherapy in the treatment of malignant glioma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-382. doi:10.1158/1538-7445.AM2011-LB-382

Decoy Strategies: The Structure of TL1A:DcR3 Complex

Decoy Receptor 3 (DcR3), a secreted member of the Tumor Necrosis Factor (TNF) receptor superfamily, neutralizes three different TNF ligands: FasL, LIGHT, and TL1A. Each of these ligands engages unique signaling receptors which direct distinct and critical immune responses. We report the crystal structures of the unliganded DcR3 ectodomain and its complex with TL1A, as well as complementary mutagenesis and biochemical studies. These analyses demonstrate that DcR3 interacts with invariant backbone and side-chain atoms in the membrane-proximal half of TL1A which supports recognition of its three distinct TNF ligands. Additional features serve as antideterminants that preclude interaction with other members of the TNF superfamily. This mode of interaction is unique among characterized TNF:TNFR family members and provides a mechanistic basis for the broadened specificity required to support the decoy function of DcR3, as well as for the rational manipulation of specificity and affinity of DcR3 and its ligands.

Phosphatidylinositol 3-Kinase Facilitates Microtubule-dependent Membrane Transport for Neuronal Growth Cone Guidance

The activity of PI3K is necessary for polarized cell motility. To guide extending axons, environmental cues polarize the growth cone via asymmetric generation of Ca(2+) signals and subsequent intracellular mechanical events, including membrane trafficking and cytoskeletal reorganization. However, it remains unclear how PI3K is involved in such events for axon guidance. Here, we demonstrate that PI3K plays a permissive role in growth cone turning by facilitating microtubule (MT)-dependent membrane transport. Using embryonic chick dorsal root ganglion neurons in culture, attractive axon turning was induced by Ca(2+) elevations on one side of the growth cone by photolyzing caged Ca(2+) or caged inositol 1,4,5-trisphosphate. We show that PI3K activity was required downstream of Ca(2+) signals for growth cone turning. Attractive Ca(2+) signals, generated with caged Ca(2+) or caged inositol 1,4,5-trisphosphate, triggered asymmetric transport of membrane vesicles from the center to the periphery of growth cones in a MT-dependent manner. This centrifugal vesicle transport was abolished by PI3K inhibitors, suggesting that PI3K is involved in growth cone attraction at the level of membrane trafficking. Consistent with this observation, immunocytochemistry showed that PI3K inhibitors reduced MTs in the growth cone peripheral domain. Time-lapse imaging of EB1 on the plus-end of MTs revealed that MT advance into the growth cone peripheral domain was dependent on PI3K activity: inhibition of the PI3K signaling pathway attenuated MT advance, whereas exogenous phosphatidylinositol 3,4,5-trisphosphate, the product of PI3K-catalyzed reactions, promoted MT advance. This study demonstrates the importance of PI3K-dependent membrane trafficking in chemotactic cell migration.

Guidelines on the use of etanercept for juvenile idiopathic arthritis in Japan

Etanercept is a dimeric fusion protein consisting of the extracellular domain of human tumor necrosis factor receptor II (TNFR II, molecular weight 75 kDa) coupled to the Fc region of human immunoglobulin (IgG1). It is produced by recombinant DNA technology by first introducing the gene into Chinese hamster ovarian cells and then purifying the protein from the culture supernatant. The mechanism of action of etanercept consists of binding to serum TNF-alpha and lymphotoxin (LT)-alpha (TNF-beta), which prevents TNF-alpha and LT-alpha from binding to the TNF-alpha receptor on the plasma membrane of the target cell. Etanercept is currently approved for treating adult rheumatoid arthritis (RA) in more than 70 countries worldwide. In Japan, it was approved for this target group in January 2005. The USA and Europe were the first to approve entanercept for use in treating juvenile idiopathic arthritis (JIA), initially for the treatment of active polyarticular JIA in patients not responding to disease-modifying antirheumatic drugs (USA in May 1999, followed by the EU in February 2000). Thereafter, the drug received approval for the treatment of JIA in many other countries. In Japan, children who have been diagnosed and treated according to Yokota et al. (Mod Rheumatol 17:353-363, 2007), but who have responded poorly to treatment must move onto the next stage of treatment. Such treatments include biological drugs, which, however, should be used with strict adhesion to the indications and exclusion criteria and should be used, for the time being, only by physicians trained on how to use them. In Japan, etanercept was approved in July 2009 for use in children. Although this drug has brought about a revolutionary advance in the treatment of JIA, it is our task to maximize its therapeutic effects and minimize its toxic effects. The guidelines presented here define the indications, exclusion criteria, usage, and evaluation criteria of etanercept for the treatment of polyarticular JIA.

Production of recombinant human erythropoietin/Fc fusion protein by genetically manipulated chickens

We previously reported the production of human erythropoietin (hEpo) using genetically manipulated (GM) chickens. The recombinant hEpo was produced in the serum and egg white of the GM chickens, and the oligosaccharide chain structures of the serum-derived hEpo were more favorable than those of the egg white-derived hEpo. In the present study, a retroviral vector encoding an expression cassette for a fusion protein of hEpo and the Fc region of human immunoglobulin G (hEpo/Fc) was injected into developing chicken embryos, with the aim of recovering the serum-derived hEpo from egg yolk through the yolk accumulation mechanism of maternal antibodies. The GM chickens that hatched stably produced the hEpo/Fc fusion protein not only in their serum and egg white, but also in the egg yolk as expected. Lectin blot analyses revealed that significant amounts of the oligosaccharide chains of hEpo/Fc produced in the serum and eggs of GM chickens terminated with galactose, and that the oligosaccharide chains of the serum- and yolk-derived hEpo/Fc incorporated sialic acid residues. Moreover, biological activity assessment using Epo-dependent cells revealed that the yolk-derived hEpo/Fc exhibited a comparable performance to the serum- and CHO-derived hEpo/Fc. These results indicate that transport of Fc fusion proteins from the blood circulation to the yolk in chickens represents an effective strategy for the production of pharmaceutical glycoproteins using transgenic chicken bioreactors.

Cadherin Conformations Associated with Dimerization and Adhesion

To investigate conformations of C-cadherin associated with functional activity and physiological regulation, we generated monoclonal antibodies (mAbs) that bind differentially to monomeric or dimeric forms. These mAbs recognize conformational epitopes at multiple sites along the C-cadherin ectodomain aside from the well known Trp-2-mediated dimer interface in the N-terminal EC1 domain. Group 1 mAbs, which bind monomer better than dimer and the Trp-2-mutated protein (W2A) better than wild type, recognize epitopes in EC4 or EC5. Dimerization of the W2A mutant protein via a C-terminal immunoglobulin Fc domain restored the dimeric mAb-binding properties to EC4-5 and partial homophilic binding activity but did not restore full cell adhesion activity. Group 2 and Group 3 mAbs, which bind dimer better than monomer and wild type better than W2A, recognize epitopes in EC1 and the interface between EC1 and EC2, respectively. None of the mAbs could distinguish between different physiological states of C-cadherin at the cell surface of either Xenopus embryonic cells or Colo 205 cultured cells, demonstrating that changes in dimerization do not underlie regulation of adhesion activity. On the cell surface the EC3-EC5 domains are much less accessible to mAb binding than EC1-EC2, suggesting that they are masked by the state of cadherin organization or by other molecules. Thus, the EC2-EC5 domains either reflect, or are involved in, cadherin dimerization and organization at the cell surface.

Weak Interaction between Inhibition Peptides and a Soluble Receptor of Fusion Protein in the Liquid Phase

Fluorescence polarization analysis (FPA) of a liquid-phase method was carried out with a glycosylphosphatidylinositol (GPI) anchored membrane receptor bone marrow stromal cell antigen 1 (BST-1, CD157) as a model receptor for medical screening. A soluble receptor, BST1-Fc, was prepared by fusing the extracellular domain of BST-1 and the Fc region of human immunoglobulin G (IgG). The binding curves of BST1-Fc with a fluorescently labeled ligand peptide, or its three derivatives, were developed using ordinary FPA in the liquid phase. The obtained dissociation constants (Kd) were comparable with those reported as measured with SPR of a solid-phase method, except for one derivative peptide with Kd larger than 7000 nM. Competitive FPA was carried out, and it was demonstrated that a very weak interaction, which would be difficult to detect with SPR or other solid-phase methods, could be analyzed with both ordinary and competitive FPA.

Hexamer peptide affinity resins that bind the Fc region of human immunoglobulin G

Abstract: A family of linear hexapeptides composed of histidine on the N‐terminus followed by aromatic amino acid(s) and positively charged amino acid(s) has been identified through a three‐step screening of a synthetic solid phase library. These peptides were able to recognize human immunoglobulin G (HIgG) through its Fc region, and their selectivity to Fc is comparable to Protein A. This is the first known report of short peptides that are able to bind HIgG by recognizing its Fc portion. One of the ligands from the identified family, HWRGWV, was examined for its ability to isolate HIgG from complex mixtures. It was found that HWRGWV possessed the potential to purify HIgG from complete mammalian cell culture medium containing 10% fetal calf serum with purity comparable to commercially available resins, but using milder elution conditions. HWRGWV bound all HIgG subclasses and IgGs from bovine, mouse, goat, and rabbit. The broad affinity spectrum as well as its Fc recognition ability may be useful in capturing and detecting both polyclonal and monoclonal antibodies.