Makoto Ohtsu

Inhibition of apoptosis by the actin-regulatory protein gelsolin

Gelsolin is an actin‐regulatory protein that modulates actin assembly and disassembly, and is believed to regulate cell motility in vivo through modulation of the actin network. In addition to its actin‐regulatory function, gelsolin has also been proposed to affect cell growth. Our present experiments have tested the possible involvement of gelsolin in the regulation of apoptosis, which is significantly affected by growth. When overexpressed in Jurkat cells, gelsolin strongly inhibited apoptosis induced by anti‐Fas antibody, C2‐ceramide or dexamethasone, without changing the F–actin morphology or the levels of Fas or Bcl‐2 family proteins. Upon the induction of apoptosis, an increase in CPP32(‐like) protease activity was observed in the control vector transfectants, while it was strongly suppressed in the gelsolin transfectants. Pro‐CPP32 protein, an inactive form of CPP32 protease, remained uncleaved by anti‐Fas treatment in the gelsolintransfectants, indicating that gelsolin blocks upstream of this protease. The tetrapeptide inhibitor of CPP32(‐like) proteases strongly inhibited Fas‐mediated apoptosis, but only partially suppressed both C2‐ceramide‐ and dexamethasone‐induced apoptosis. These data suggest that the critical target responsible for the execution of apoptosis may exist upstream of CPP32(‐like) proteases in Jurkat cells and that gelsolin acts on this target to inhibit the apoptotic cell death program.

Determination of Carrier Status for the Wiskott-Aldrich Syndrome by Flow Cytometric Analysis of Wiskott-Aldrich Syndrome Protein Expression in Peripheral Blood Mononuclear Cells

The Wiskott-Aldrich syndrome (WAS) is caused by defects in the WAS protein (WASP) gene on the X chromosome. Previous study disclosed that flow cytometric analysis of intracellular WASP expression (FCM-WASP analysis) in lymphocytes was useful for the diagnosis of WAS patients. Lymphocytes from all WAS patients showed WASPdim instead of WASPbright. Here we report that FCM-WASP analysis in monocytes could be a useful tool for the WAS carrier diagnosis. Monocytes from all nine WAS carriers showed varied population of WASPdim together with WASPbright. None of control individuals possessed the WASPdim population. In contrast, lymphocytes from all the carriers except two lacked the WASPdim population. The difference of the WASPdim population in monocytes and lymphocytes observed in WAS carriers suggests that WASP plays a more critical role in the development of lymphocytes than in that of monocytes. The present studies suggest that a skewed X-chromosomal inactivation pattern observed in WAS carrier peripheral blood cells is not fixed at the hemopoietic stem cell level but progresses after the lineage commitment.

Genetic studies of three japanese patients with p22-phox-deficient chronic granulomatous disease : detection of a possible common mutant CYBA allele in japan and a genotype-phenotype correlation in these patients

Chronic granulomatous disease (CGD) is a disorder caused by defects in the NADPH oxidase responsible for superoxide generation in phagocytes. Cytochrome b558, an essential component of this enzyme, is a heterodimer formed by a 91 kDa glycoprotein (gp91‐phox) and a 22 kDa polypeptide (p22‐phox). Mutations in the p22‐phox gene (CYBA) locus in 16q24 result in one of the rare autosomal recessive forms of CGD. We performed mutation analysis in three female CGD patients suspected of having this form of the disease and found two novel mutations in CYBA. Whereas patient 1 with severe phenotype had a homozygous nonsense mutation in exon 1 (C‐35 → T, Gln‐3 → stop), patients 2 and 3 with mild phenotype shared the same homozygous missense mutation in exon 2 (G‐98 → A, Gly‐24 → Arg). None of the parents of patients 2 and 3 is related. Therefore, this mutation could be a hot‐spot or a common mutation in the Japanese population. Patients 2 and 3, but not patient 1, were demonstrated to have detectable p22‐phox expression and significant granulocyte respiratory burst (ROB) activity. In this study, we were able to demonstrate an excellent correlation between genotype, p22‐phox expression, ROB activity and clinical phenotype in these patients.

Successful Treatment with Methylprednisolone Pulse Therapy for a Life-Threatening Pulmonary Insufficiency in a Patient with Chronic Granulomatous Disease following Pulmonary Invasive Aspergillosis and Burkholderia cepacia Infection

A 14-year-old boy with X-linked chronic granulomatous disease developed severe invasive pulmonary aspergillosis. He was treated with itraconazole and amphotericin B. However, he deteriorated with progressive pulmonary lesions. Burkholderia cepacia was isolated from his bronchoalveolar lavage. Finally, he was given granulocyte transfusions. Following this procedure, his condition rapidly worsened leading to respiratory failure. His lung biopsy demonstrated organizing pneumonia at his right middle lobe. Then, a methylprednisolone pulse therapy was initiated together with the administration of appropriate antibiotics and adequate amounts of amphotericin B. Dramatically, his condition improved. Therefore, a methylprednisolone pulse therapy with appropriate antimicrobial drugs seems to be beneficial for severe pulmonary insufficiency in this type of patients.

Elevation of serum IgE level and peripheral eosinophil count during T lymphocyte-directed gene therapy for ADA deficiency: implication of Tc2-like cells after gene transduction procedure

We have successfully carried out T-cell-directed gene therapy for a boy with severe combined immunodeficiency due to adenosine deaminase deficiency (ADA SCID) and unexpectedly found an elevation of serum IgE level and peripheral eosinophil count during the course. More than 90% of transduced cells cultured for 7-11 days before infusion into the patient were positive for CD8 and expressed Th2-type cytokine genes such as IL-4, IL-5 and IL-13. Furthermore, CD4(+) T-depleted PBMC (peripheral blood mononuclear cells) from the patient synthesized IgE in vitro by stimulation with IL-4. Collectively, these results suggested that Tc2-like cells in the transduced cells have distinct immunological functions to help IgE synthesis and activate eosinophils.

Combined immunodeficiency, chromosomal instability, and postnatal growth deficiency in a Japanese girl

We report on an 11-year-old Japanese girl with combined immunodeficiency and chromosomal instability. She had postnatal growth deficiency and microcephaly, preaxial polydactyly of the left hand, and susceptibility to infections. Immunological studies showed marked lymphocytopenia (around 500/ll), reduced lymphocyte response to various mitogens, and reduced or absent serum IgA, IgG, and IgM. Cell biological studies of her primary skin fibroblasts demonstrated spontaneous chromosome aberrations and radiation hypersensitivity. The combination of immunodeficiency, chromosomal instability, and radiation hypersensitivity as seen in the girl is present in both ataxia-telangiectasia and Nijmegen breakage syndrome. Ataxia-telangiectasia was excluded because of differences in clinical features and laboratory data. Likewise, Nijmegen breakage syndrome is unlikely to be the case because the characteristic face, hyperpigmented spots, and mental retardation present in the syndrome were missing in the girl. Sequence analysis of a Nijmegen breakage syndrome responsible gene, NBS1, revealed no mutations. A normal NBS1 product was also demonstrated by immunoblot analysis using an anti-NBS1 antibody. We propose that the disorder in the girl represents a new combination of combined immunodeficiency and chromosomal instability.