Takashi Satoh

Heparin-dependent and -independent anti-platelet factor 4 autoantibodies in patients with systemic lupus erythematosus

OBJECTIVEnAntibodies that recognize complexes formed by platelet factor 4 (PF4) and heparin are involved in the pathogenesis of heparin-induced thrombocytopenia (HIT). This study was undertaken to investigate the prevalence and clinical correlations of anti-PF4 autoantibodies in patients with SLE.nnnMETHODSnWe studied 118 patients with SLE, 78 with primary immune thrombocytopenia (ITP), 27 with primary APS, 2 with HIT (as positive controls) and 47 healthy controls. Heparin-dependent and -independent anti-PF4 antibodies were measured with an ELISA. Antibody binding was confirmed to be heparin-dependent when inhibited by the presence of a high concentration of heparin. Pathogenic anti-PF4 antibody was assessed by serotonin-release assay.nnnRESULTSnHeparin-dependent anti-PF4 antibodies were detected in 11 SLE (9%) and 2 primary ITP (3%) patients, but at much lower levels than in HIT patients. In serotonin-release assays, only the HIT sera induced platelet activation in vitro. Heparin-independent anti-PF4 antibodies were detected in 17 SLE patients (14%). There was no correlation between the levels of heparin-dependent and -independent anti-PF4 antibodies. Cross-reactivity between these two antibodies was not detectable by ELISA competitive assay. Heparin-dependent anti-PF4 antibodies were associated with thrombocytopenia and IgM aCLs (Pu2009=u20090.007 for both comparisons), while heparin-independent anti-PF4 antibody levels were correlated with SLE disease activity index (Pu2009=u20090.0005). None of the SLE patients with anti-PF4 antibodies had previous heparin exposure.nnnCONCLUSIONnPF4 is an autoimmune target in SLE patients. Heparin-dependent and -independent anti-PF4 autoantibodies may be involved in different aspects of pathophysiology of SLE.

Fcγ receptor IIB gene polymorphism in adult Japanese patients with primary immune thrombocytopenia

To the editor:nnSeveral studies have indicated that platelet recovery occurs in a subgroup of immune thrombocytopenia (ITP) patients after successful Helicobacter pylori ( H pylori) eradication.[1][1],[2][2] Interestingly, a higher response rate to H pylori eradication therapy has been reported in

Impact of oral administration of compost extract on gene expression in the rat gastrointestinal tract.

Oral administration of an extract consisting of compost fermented with thermophiles to pigs reduces the incidence of stillbirth and promotes piglet growth. However, the mechanism by which the compost extract modulates the physiological conditions of the animals remains largely unknown. Here, we investigate the effects of compost extract on the physiological responses in the intestine of a mammalian rat model. The level of fecal immunoglobulin A (IgA), which provides protection against pathogens and is secreted from the small intestine, was significantly higher in rats treated with continuous administration of the compost extract than in untreated rats after 2 months, but not after 1 month. However, the fecal IgA level was not significantly different in rats that received the filtered compost extract compared with the untreated rats or the rats that received the compost extract. Gene expression analyses of the small intestine indicated that several immune-related genes were upregulated following compost exposure. Specifically, the expression levels of lymphocyte chemoattractant chemokine CXCL13 and Granzyme B, which is released within cytotoxic T lymphocytes and natural killer cells, increased in the small intestinal tract following compost exposure. Based on these observations, it was postulated that the increased level of fecal IgA following compost exposure was associated with the expression of CXCL13 and Granzyme B in the intestinal tract. Thus, thermophile-fermented compost could contain microbes or substances that activate the rats gut mucosal immune response.

Induction of β-catenin by the suppression of signal regulatory protein α1 in K562 cells.

The signal regulatory protein (SIRP) α1 is a cell surface receptor expressed predominantly in monocytes, granulocytes, dendritic cells, as well as hematopoietic stem cells. In contrast, SIRPα1 expression is significantly reduced in the majority of myeloid malignancies. SIRPα1 is a negative regulator of signaling and its reduced expression is considered to play a role in the pathogenesis of these diseases through aberrant signaling. To identify SIRPα1 downstream target genes, we established SIRP α1-knockdown chronic myeloid leukemia K562 (K562SIRPα1KD) cells expressing reduced levels of SIRPα1 by stably transfecting SIRPα1 siRNAs. Microarray analysis demonstrated that several genes, including β-catenin, were significantly induced in K562SIRPα1KD cells. Real-time PCR and Western blot analyses, confirmed the induction of this gene. Phosphorylation of Ser9 of glycogen synthesis kinase (GSK) -3β, results in the inactivation of GSK-3β, leading to the induction of β-catenin. We found significant phosphorylation of extracellular signal-regulated kinase (ERK), Akt, as well as of GSK-3β-Ser9, which may play a role in the up-regulation of β-catenin in K562SIRPα1KD cells. To our knowledge, this is a first report demonstrating the relationships between SIRPα1 and β-catenin in leukemia cells.

Thermophile-fermented compost as a possible scavenging feed additive to prevent peroxidation

The extract of compost from fermented marine animals and thermophiles, including Bacillaceae, confers health benefits as a feed additive for fish and pigs. However, little research has explored how such compost extracts affect the physiological functions of the animals. In this study, the physiological effects of oral administration of the compost extract on the liver and muscle of rats are evaluated. After long-term administration of the compost extract in rats fed with either a normal diet or a high-fat diet over 3 months, accumulation of lipid peroxide and malondialdehyde, a marker of peroxidation, in the livers was reduced. Under such conditions, the unsaturated fatty acid composition in the liver was not significantly different in the rats fed either with or without the compost extract. In contrast, analyzes of 2,2-diphenyl-1-picrylhydrazyl (DPPH) revealed that free-radical-scavenging activity was increased in the livers of rats fed with the compost extract, although the extract itself had little of this activity. Glutathione, an antioxidant, was slightly increased following compost exposure. In addition, the levels of glutamate and glutamine, sources of glutathione, were slightly raised. Such a tendency was also observed in the muscle. Thus, thermophile-fermented compost can be a fermented feed additive to prevent peroxidation in the liver and muscle, and the effects of this additive may, in part, be associated with the retention of antioxidants and free amino acids within the organs.

Regulatory mechanism of silkworm hemocyte adhesion to organs.

Circulating hemocytes in the body fluid of the silkworm are increased during the larval-larval molting period. We investigated hemocyte adhesion to organs mediating the selectin-selectin ligands during the feeding period and the larval-larval molting period using the lectin staining method, sugar chain digestion test with glycoside hydrolases, and the hemocyte adhesion inhibition test using monosaccharides. The results of these tests suggested that the selectin ligand involved in hemocyte adhesion was the Sialyl Lewis x-type, and the structure was changed from the feeding period to the larval-larval molting period. Beta-galactosidase appears to be an enzyme that eliminates N-acetylgalactosamine and sialylated N-acetylgalactosamine from the terminal of Sialyl Lewis x. Beta-galactosidase activation in skin basement membranes, muscle, fat bodies, midguts, and hemocytes increased markedly during the larval-larval molting period, and at that time, hemocytes were detached from organs. Adding 20-hydroxyecdysone or its analog, tebufenozide to cultured fat bodies increased &bgr;-galactosidase activity in these tissues. Therefore, 20-hydroxyecdysone may induce a structural change in Sialyl Lewis x type sugar chains on the cell surface of silkworms organs by increasing the &bgr;-galactosidase activity to detach hemocytes from organs and increase the number of circulating hemocytes during the larval-larval molting period.

Differential Diagnosis: Secondary ITP

There is no substantial difference in immunologic pathophysiology between primary and secondary immune thrombocytopenia (ITP): it is characterized by increased platelet destruction in the reticuloendothelial system or reduced platelet production mediated primarily by IgG antiplatelet autoantibodies, resulting in thrombocytopenia. Secondary ITP can occur in the context of a variety of underlying diseases or conditions, including autoimmune diseases, such as systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS), lymphoproliferative disorders, and chronic infection with certain bacterial or viral microorganisms, including Helicobacter pylori (H. pylori), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Therefore, patients diagnosed as having ITP should be further evaluated for symptoms, physical signs, and laboratory tests associated with underlying disorders that potentially cause secondary ITP. It is imperative to consider risk factors in an individual patient basis. For example, elderly in H. pylori epidemic countries, such as East Asia and Italy, should be considered for performing H. pylori testing, homosexuals and drug abusers for performing HIV and HCV testing, and young women with a rash, fever, or arthralgia for performing a series of autoantibody tests. In clinical practice, identification of underlying diseases or conditions is essential in patients diagnosed as having ITP since treatment strategies are often different between primary and secondary ITP.

T-Cell Abnormalities

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by increased platelet destruction and reduced platelet production caused primarily by IgG antiplatelet autoantibodies, which mainly target platelet membrane glycoproteins (GPs), including GPIIb/IIIa and GPIb/IX. GPIIb/IIIa-reactive CD4+ T cells play a central role in the pathogenic process by triggering and maintaining antiplatelet autoantibodies. The mechanism for ongoing antiplatelet antibody production is explained by a “pathogenic loop” model consisting of macrophages in the reticuloendothelial system, GPIIb/IIIa-reactive CD4+ T cells, and B cells producing antiplatelet antibodies. Among T helper (Th) cell subsets, Th1 and Th17 cells as well as newly identified T follicular helper (Tfh) cells, which support B cell maturation and differentiation within the germinal center, are actively involved in antiplatelet antibody production. Finally, platelet-reactive CD8+ cytotoxic T cells directly induce lysis and apoptosis of circulating platelets as well as megakaryocytes. On the other hand, CD4+ regulatory T cells (Tregs), which contribute to maintenance of peripheral immune tolerance, are defective in patients with ITP, through decreased numbers and impaired function of Tregs. In fact, mice lacking Foxp3 Tregs spontaneously develop chronic thrombocytopenia mediated through the production of IgG antiplatelet autoantibodies. Further studies evaluating mechanisms for T-cell dysregulation are useful in elucidating the pathogenesis of ITP and in developing novel treatment strategies.