Yoshiharu Tokimitsu

Single lymphocyte analysis with a microwell array chip.

Following genomics and proteomics, cytomics, a novel method of looking at life, has emerged for analyzing large populations of cells on a single‐cell basis with multiple parameters in a quantitative manner. We have developed a highly integrated live‐cell microarray system for analyzing the cellular responses of individual cells using a microwell array chip that has 234,000 microwells each of which is just large enough to fit a single cell. Compared with flow cytometry and microscope‐based methods, our system can analyze the history of the cellular responses of a large number of cells. We have successfully applied the system to analyze human antigen‐specific B‐cells and produced human monoclonal antibodies (MoAb) against hepatitis B virus surface antigen. We have also constructed a mouse system to assess hepatitis B virus‐neutralization activity and have demonstrated the neutralization activity of our antibodies. Our technology should expand the horizons of cell analysis as well as enable generation of human MoAb for antibody‐based therapeutics and diagnosis for infectious diseases such as hepatitis viruses.

Cell-microarray analysis of antigen-specific B-cells: single cell analysis of antigen receptor expression and specificity.

The authors previously developed a cell‐microarray system that effectively detects antigen‐specific B‐cells by monitoring intracellular Ca2+ at single cell levels. Here they present a novel method to detect antigen‐specific B‐cells using cell‐microarray system. To detect antigen‐specific B‐cells, they arrayed live lymphocytes on a chip, stained cells with fluorescence‐labeled nonspecific proteins, and analyzed them with a fluorescence scanner to detect nonspecific protein binding to B‐cells. They then stained cells with fluorescence‐labeled antigen and analyzed them with the scanner. Cells stained with specific antigen, but not with nonspecific proteins, were determined as antigen‐specific B‐cells and harvested. Antibody cDNA was amplified from retrieved B‐cells by single‐cell RT‐PCR, inserted into expression vectors, and was examined for its specificity by ELISA. They could detect antigen‐specific B‐cells at a frequency of 0.01% in a model system using transgenic mice that express antibody to hen‐egg lysozyme on the surface of B‐cells. They applied this system to directly detect hepatitis B virus surface‐antigen (HBs‐Ag)‐specific B‐cells from peripheral blood in HBs‐Ag‐vaccinated volunteers and succeeded in producing HBs‐Ag‐specific monoclonal antibody. This novel system allows us to identify human antigen‐specific B‐cells of very low frequency and is a powerful tool to explore the candidates of antibody therapeutics.

Respiratory involvement in IgG4-related Mikulicz’s disease

Abstract‘Immunoglobulin G4 (IgG4)-related disease’ is a new clinical concept of multi-organ diseases, with Mikulicz’s disease (MD) being a clinical phenotype of IgG4-related disease. To clarify the clinical characteristics of respiratory involvement associated with IgG4-related MD, we retrospectively assessed 25 patients with MD, 11 (44%) of whom had allergic symptoms, and 7 (28%) of whom complained of respiratory problems. Thirteen patients (52%) presented with pulmonary and/or mediastinal lesions (P-MD) on chest computed tomography (CT), and 11 (44%) had lesions limited to the lacrimal and/or salivary glands (L-MD). Mean serum total protein, IgG, and IgG4 concentrations were significantly higher and CH50 was significantly lower in the P-MD than in the L-MD group. Immune complex was present only in the P-MD group. Chest CT images showed bronchial wall thickening, consolidation, nodule(s), interlobular thickening, ground glass opacity, pleural thickening/effusion, and mediastinal lymphadenopathy. Five of seven patients who underwent histological examination of the lungs had abundant IgG4-positive plasma cell infiltrates (IgG4/IgG-positive plasma cells >40%), but the other two did not. These findings suggest that respiratory lesions are not rare in patients with IgG4-related MD, and that they present with various manifestations. IgG4-related MD should be differentiated from similar diseases, such as sarcoidosis, bronchial asthma, Sjögren’s syndrome, and malignant lymphoma.

Development of osteomalacia in a post-liver transplant patient receiving adefovir dipivoxil

We report the case of a patient treated with living donor-related liver transplantation who suffered from osteomalacia during adefovir dipivoxil (ADV)-containing antiviral therapy for lamivudine-resistant hepatitis B virus infection. The patient had generalized bone pain, with severe hypophosphatemia after 20 mo of ADV therapy. Radiographic studies demonstrated the presence of osteomalacia. The peak plasma ADV level was 38 ng/mL after administration of ADV at 10 mg/d. It was also found that ADV affected the metabolism of tacrolimus, a calcineurin-inhibitor, and caused an increase in the plasma levels of tacrolimus. The disability was reversed with the withdrawal of ADV and with mineral supplementation. ADV can cause an elevation of plasma tacrolimus levels, which may be associated with renal dysfunction. High levels of ADV and tacrolimus can cause nephrotoxicity and osteomalacia. This case highlights the importance of considering a diagnosis of osteomalacia in liver transplantation recipients treated with both ADV and tacrolimus.

Analysis of the epitope and neutralizing capacity of human monoclonal antibodies induced by hepatitis B vaccine.

Hepatitis B virus (HBV) is an infectious agent that is a significant worldwide public health issue. However, the mechanism by which vaccination-induced antibodies prevent HBV infection remains unclear. To investigate the mechanism by which antibodies induced by hepatitis B surface Ag (HBsAg)-vaccination prevent HBV infection in humans, we prepared human monoclonal antibodies (mAbs) against HBsAg using a novel cell-microarray system from peripheral blood B-lymphocytes from vaccinated individuals. We then characterized the IgG subclass, L-chain subtype, and V-gene repertoire of the H/L-chain, as well as affinities of each of these mAbs. We also determined the epitopes of the individual mAbs using synthesized peptides, and the HBV-neutralizing activities of mAbs using the hepatocyte cell line HepaRG. Consequently, IgG1 and kappa chain was mainly used as the mAbs for HBsAg. Seventy percent of the mAbs bound to the loop domain of the small-HBsAg and showed greater neutralizing activities. There were no relationships between their affinities and neutralization activities. A combination of mAbs recognizing the first loop domain showed a synergistic effect on HBV-neutralizing activity that surpassed conventional hepatitis B-Ig (HBIG) in the HepaRG cell line assay. These results may contribute to the development of effective mAb treatment against HBV infection replacing conventional HBIG administration.

Possible involvement of glial cell line‐derived neurotrophic factor and its receptor, GFRα1, in survival and maturation of thymocytes

The glial cell line‐derived neurotrophic factor (GDNF) and its receptors (GFR) play important roles in the promotion of survival and differentiation of central and peripheral neuronal populations. We show that GFRα1, a component of GDNF receptor, was expressed in thymocytes at an early stage of thymocyte‐development and was involved in the survival of thymocyte precursors. GFRα1and GDNF were expressed in thymus, but not in spleen or lymph nodes in adult mice. During embryonic thymocyte development, GFRα1 was predominantly expressed on thymocytes from days 14.5 to 16.5 of gestation, and thereafter its expression gradually declined. In adult thymus, GFRα1 was expressed only on CD4–CD8– double‐negative (DN) thymocytes, but not on CD4+CD8+ double‐positive or single‐positive thymocytes. It was strongly expressed on RAG2–/– thymocytes arrested at the DN stage, and ist expression was reduced during their differentiation after in vivo anti‐CD3 antibody stimulation. Additionally, fetal thymocyte precursors grew in serum‐free medium of the fetal thymus organ culture system in the presence of recombinant GDNF (rGDNF), while the cells without rGDNF died. These results suggested that GDNF/GFRα1 are involved in the survival of both the nervous system and DN immature thymocytes.

Survival Benefit of Tolvaptan for Refractory Ascites in Patients with Advanced Cirrhosis

Aims: The study aimed to evaluate the effects of tolvaptan treatment on survival of patients with decompensated liver cirrhosis with refractory ascites. Methods: This multicenter, retrospective, observational study included patients with cirrhosis who were treated with tolvaptan for hepatic ascites refractory to conventional diuretics. Patients who could and could not decrease accompanying diuretics within 1 month after tolvaptan administration were defined as the “Decreased” and “Not-decreased” groups, respectively. Results: Median body weight change 1 week after tolvaptan treatment was –1.95 kg, with the 50% of patients experiencing a 2 kg/week reduction. Spot urinary sodium was found to be a better predictor of tolvaptan response than liver function and liver fibrosis markers. Median survival was significantly longer (not reached versus 116 days, p = 0.005) and serum creatinine concentrations 12 weeks after tolvaptan administration significantly lower (0.99 vs. 1.55 mg/dL, p < 0.05) in the Decreased than in the Not-decreased group. Multivariate analysis showed that the presence of viable hepatocellular carcinoma (hazards ratio [HR] 2.14, p = 0.02) and a decrease in diuretics were independently prognostic of survival (HR 0.36, p < 0.01). Conclusions: The maintenance of renal function is essential in enhancing survival of patients with cirrhosis. Doses of diuretics should be adjusted appropriately during tolvaptan treatment.

Trapping and Collection of Lymphocytes Using Microspot Array Chip and Magnetic Beads

A microspot array chip, which has microspots of a magnetic thin film patterned on a glass substrate, was fabricated for trapping individual cells and for measuring their cellular response. The chip was easily fabricated by conventional semiconductor fabrication techniques on a mass production level as a disposable medical device. When a solution of lymphocyte-bound-magnetic beads was poured into the magnetized chip, each lymphocyte was trapped on each microspot of the magnetic thin film. The trapped cells were easily recovered from the chip using a micromanipulator. The micro-spot array chip can be utilized for arraying live cells and for measuring the response of each cell. The chip will be useful for preparing on array of different kinds of cells and for analyzing cellular response at the single cell level. The chip will be particularly useful for detecting antigen-specific B-lymphocytes and antigen-specific antibody complementary deoxyribonucleic acid (cDNA).