Hideharu Anazawa

The absence of fucose but not the presence of galactose or bisecting N-acetylglucosamine of human IgG1 complex-type oligosaccharides shows the critical role of enhancing antibody-dependent cellular cytotoxicity

An anti-human interleukin 5 receptor (hIL-5R) humanized immunoglobulin G1 (IgG1) and an anti-CD20 chimeric IgG1 produced by rat hybridoma YB2/0 cell lines showed more than 50-fold higher antibody-dependent cellular cytotoxicity (ADCC) using purified human peripheral blood mononuclear cells as effector than those produced by Chinese hamster ovary (CHO) cell lines. Monosaccharide composition and oligosaccharide profiling analysis showed that low fucose (Fuc) content of complex-type oligosaccharides was characteristic in YB2/0-produced IgG1s compared with high Fuc content of CHO-produced IgG1s. YB2/0-produced anti-hIL-5R IgG1 was subjected to Lens culinaris aggulutin affinity column and fractionated based on the contents of Fuc. The lower Fuc IgG1 had higher ADCC than the IgG1 before separation. In contrast, the content of bisecting GlcNAc of the IgG1 affected ADCC much less than that of Fuc. In addition, the correlation between Gal and ADCC was not observed. When the combined effect of Fuc and bisecting GlcNAc was examined in anti-CD20 IgG1, only a severalfold increase of ADCC was observed by the addition of GlcNAc to highly fucosylated IgG1. Quantitative PCR analysis indicated that YB2/0 cells had lower expression level of FUT8 mRNA, which codes α1,6-fucosyltransferase, than CHO cells. Overexpression of FUT8 mRNA in YB2/0 cells led to an increase of fucosylated oligosaccharides and decrease of ADCC of the IgG1. These results indicate that the lack of fucosylation of IgG1 has the most critical role in enhancement of ADCC, although several reports have suggested the importance of Gal or bisecting GlcNAc and provide important information to produce the effective therapeutic antibody.

Structure of the mouse klotho gene and its two transcripts encoding membrane and secreted protein

We previously established a novel mouse model for human aging and identified the genetic foundation responsible for it. A defect in expression of a novel gene, termed klotho (kl), leads to a syndrome resembling human aging in mice. The kl gene encodes a single‐pass membrane protein whose extracellular domain carries homology to β‐glucosidases. In this report, we present the entire mouse kl gene organization. The mouse kl gene spans about 50 kilobases and consists of five exons. The promoter region lacks a TATA‐box and contains four potential binding sites for SP1. We further show that two kl gene transcripts encoding membrane or secreted protein are generated through alternative transcriptional termination. These findings provide fundamental information for further study of the kl gene which may regulate aging in vivo.

Improvement of multiple pathophysiological phenotypes of klotho (kl/kl) mice by adenovirus‐mediated expression of the klotho gene

We have established a novel mouse mutant, klotho (kl), by insertional mutation of a transgene and identified the structural gene. The mouse homozygous for the mutation exhibits multiple pathological conditions resembling age‐related disorders in humans and can be regarded as a model of human premature aging syndromes. However, the pathophysiological role of Klotho protein has not been clarified.

Concept for Organ Engineering: A Reconstruction Method of Rat Liver for in Vitro Culture

In the past decade, there have been remarkable advances in tissue engineering technology toward the goal of creating organoids in vitro from cells and cellular scaffolding. Indeed, tissue-engineered organoids such as skin and cartilage, each with comparatively simple architectures, are presently at the clinical stage. However, conventional tissue engineering techniques have not allowed for the reconstruction of an organoid that mimics an organ of complex architecture of abundant vascular networks. We established a method for organ engineering that can remodel a rat liver into a reconstructed organoid without separating the majority of liver cells by a continuous three-step perfusion. The liver was perfused through its vascular system with a buffered balanced salt solution to cleanse blood from the organ, with a collagenase/dispase medium to deconstruct cellular scaffolds, and with a culture medium containing collagen type I to reorganize the multicellular architecture. The reconstructed organoid was then prepared by excising the perfused liver from the rat and culturing it at 37 degrees C for 2 h. Histologically healthy parenchymal hepatocytes expressing albumin were observed in the excised organoid even after culture for 3 weeks. Furthermore, a fibroblast-implanted organoid was prepared by using a culture medium containing suspended fibroblasts in the third step of the perfusion procedure, demonstrating the efficacy of heterogeneous cells for the reconstruction of an organoid. This method may be applicable to the formation of organoids from other organs, such as kidney and spleen, each of which have abundant capillaries, and therefore the method provides a novel concept for the development of lab-grown organs, i. e., organ engineering.

Establishment of humanized anti-interleukin-5 receptor alpha chain monoclonal antibodies having a potent neutralizing activity

Human interleukin-5 is the key cytokine involved in regulating the production and function of human eosinophils. IL-5 binds to its specific receptor composed of two heterogeneous alpha and beta polypeptide chains (hIL-5Ralpha and betac) that are expressed on the cell surface. The hIL-5Ralpha specifically binds IL-5 without involvement of the betac. It has been suggested that neutralizing antibodies to hIL-5Ralpha could serve as a therapeutic agent in eosinophil-associated diseases. We describe here the creation and biologic activities of a mouse monoclonal antibody against hIL-5Ralpha that blocks the following IL-5 dependent activities (a) binding of the IL-5 ligand to its receptor, (b) IL-5 dependent growth of hIL-5R expressing cells, and (c) IL-5-induced adhesion of human eosinophils. We also describe the process for humanization of the mouse Mab towards development of a therapeutic MAb. The humanized version of the monoclonal antibody also displayed potent neutralizing activity against IL-5 dependent activities.

Reconstitution of telomerase activity utilizing human catalytic subunit expressed in insect cells.

Telomerase is a specialized reverse transcriptase responsible for maintaining the termini of linear chromosomes. The human enzyme is a ribonucleoprotein complex minimally comprising a catalytic protein moiety (hTERT) and an RNA subunit (hTR) which acts as the template for the reverse transcriptase reaction. Here we report expression of recombinant hTERT protein in insect cells utilizing a baculovirus expression system. The recombinant hTERT protein reconstitutes telomerase activity in the presence of hTR, either when co-expressed in insect cells or when added in vitro. Reconstitution of telomerase activity using this system will facilitate further analysis of the biochemical and biophysical properties of this enzyme.