Search PubMed⌕ Search

Biomedical subjects

Teizo Fujita

Publications and source records attributed to Teizo Fujita.

At least 19 recordsLinked to original sources
PubMed2006

Glomerular activation of the lectin pathway of complement in IgA nephropathy is associated with more severe renal disease.

IgA nephropathy (IgAN) is characterized by glomerular co-deposition of IgA and complement components. Earlier studies showed that IgA activates the alternative pathway of complement, whereas more recent data also indicate activation of the lectin pathway. The lectin pathway can be activated by binding of mannose-binding lectin (MBL) and ficolins to carbohydrate ligands, followed by activation of MBL-associated serine proteases and C4. This study examined the potential role of the lectin pathway in IgAN. Renal biopsies of patients with IgAN (n=60) showed mesangial deposition of IgA1 but not IgA2. Glomerular deposition of MBL was observed in 15 (25%) of 60 cases with IgAN and showed a mesangial pattern. All MBL-positive case, but none of the MBL-negative cases showed glomerular co-deposition of L-ficolin, MBL-associated serine proteases, and C4d. Glomerular deposition of MBL and L-ficolin was associated with more pronounced histologic damage, as evidenced by increased mesangial proliferation, extracapillary proliferation, glomerular sclerosis, and interstitial infiltration, as well as with significantly more proteinuria. Patients who had IgAN with or without glomerular MBL deposition did not show significant differences in serum levels of MBL, L-ficolin, or IgA or in the size distribution of circulating IgA. Furthermore, in vitro experiments showed clear binding of MBL to polymeric but not monomeric patient IgA, without a significant difference between both groups. Together, these findings strongly point to a role for the lectin pathway of complement in glomerular complement activation in IgAN and suggest a contribution for both MBL and L-ficolin in the progression of the disease.

Adult↗
PubMed2006

Lectin complement system and pattern recognition.

Living organisms have strong defense mechanisms against invading microorganisms as survival strategies. One of the defense mechanisms is the complement system, composed of more than 30 serum and cell surface components. This system collaborates in recognition and elimination of pathogens as a part of both the innate and acquired immune systems. The two collagenous lectins, mannose-binding lectin (MBL) and ficolins, are pattern recognition proteins acting in innate immunity and, upon recognition of the pathogens, they trigger the activation of the lectin complement pathway through attached serine proteases (MASPs). A similar lectin-based complement system, consisting of the lectin-protease complex and C3, is present in ascidians, our closest invertebrate relatives and in lamprey, the most primitive vertebrate. Furthermore, a lamprey N-acetylglucosamine (GlcNAc)-binding lectin was identified as the orthlogue of mammalian C1q, and lamprey MASP is suggested as the prototype of MASP-2/C1r/C1s, indicating that the classical complement pathway arose as a part of the innate immune system. Thus, the complement system is one of the most highly organized innate immune systems in invertebrates and jawless vertebrates, and this system has survived in vertebrates with its core components little changed for 600-700 million years.

Amino Acid Sequence↗
PubMed2006

Cloning and characterization of mannose-binding lectin from lamprey (Agnathans).

The recognition of pathogens is mediated by a set of pattern recognition molecules that recognize conserved pathogen-associated molecular patterns shared by broad classes of microorganisms. Mannose-binding lectin (MBL) is one of the pattern recognition molecules and activates complement in association with MBL-associated serine protease (MASP) via the lectin pathway. Recently, an MBL-like lectin was isolated from the plasma of a urochordate, the solitary ascidian. This ascidian lectin has a carbohydrate recognition domain, but the collagen-like domain was replaced by another sequence. To elucidate the origin of MBLs, the aim of this study is to determine the structure and function of the MBL homolog in lamprey, the most primitive vertebrate. Using an N-acetylglucosamine (GlcNAc)-agarose column, MBL-like lectin (p25) was isolated from lamprey serum and cDNA cloning was conducted. From the deduced amino acid sequence this lectin has a collagenous region and a typical carbohydrate recognition domain. This lectin also binds mannose, glucose, and GlcNAc, but not galactose, indicating that it is structurally and functionally similar to the mammalian MBLs. Furthermore, it associated with lamprey MASPs, and the MBL-MASP activated lamprey C3 in fluid-phase and on the surface of pathogens. In conjunction with the phylogenetic analysis, it seems likely that the lamprey MBL is an ortholog of the mammalian MBL. Because acquired immunity seems to have been established only from jawed vertebrates onward, the lectin complement pathway in lamprey, as one of the major contributors to innate immunity, plays a pivotal role in defending the body against microorganisms.

Amino Acid Sequence↗
PubMed2006

Molecular cloning and characterization of novel splicing variants of human decay-accelerating factor.

Decay-accelerating factor (DAF) is one of the complement regulatory proteins. Two isoforms of DAF have been identified in humans. In this study, we isolated novel cDNAs encoding five isoforms of DAF from the human lung, which were generated by insertion of new exonic sequences. RT-PCR revealed that all isoforms were expressed in almost all tissues tested, although the expression patterns and levels differed among the tissues. Transfection of isoform vDAF1, 2, and 3 cDNAs into CHO cells showed that these molecules are soluble forms secreted after glycosylation. Isoform vDAF4 and vDAF5 cDNAs included a part of and the entire intron 7 sequence, respectively, and the transfection of vDAF4 cDNA produced a large, glycosylated, membrane-bound form. These results suggest that more than seven isoforms of human DAF are involved in the regulation of complement activation under physiological conditions through their specific structures and localization.

Alternative Splicing↗
PubMed2005

Serum mannose-binding lectin levels in maintenance hemodialysis patients: impact on all-cause mortality.

BACKGROUND/AIMS: Mannose-binding lectin (MBL) is characteristic of an acute-phase-reacting protein like C-reactive protein (CRP). However, the prognostic value of the serum MBL level has not been examined. The aim of this study was to evaluate whether the serum MBL level can predict all-cause mortality in hemodialysis (HD) patients. METHODS: A total of 131 patients without active infection, who had been on maintenance HD for at least 2 years, were included in this study. The serum MBL, high-sensitivity CRP (hs-CRP) level, nutrition markers, and biochemical parameters were measured in June 1999. The cohort was then followed prospectively for 36 months, and clinical data were recorded. RESULTS: The MBL level of the 131 HD patients was 9.054 +/- 5.115 microg/ml (mean +/- SD). During the follow-up period, 18 patients (9 males and 9 females) died and 113 (64 males and 49 females) survived. The two leading causes of death were cardiovascular events (n = 6, 33.3%) and infection (n = 4, 22.2%). The serum MBL level was significantly lower among the nonsurvivors (6.596 +/- 4.990 microg/ml) than among the survivors (9.445 +/- 5.046 microg/ml; p < 0.05). There was a significant, although very weak, correlation between the MBL level and albumin level (p < 0.05), but there was no correlationbetween the MBL level and the hs-CRP level. The patients were divided into two groups according to the serum MBL level (< 5 and > 5 microg/ml). Multivariate analysis of factors predicting all-cause mortality in multivariate logistic regression analysis identified a serum MBL level < 5 microg/ml as a variable that independently predicted all-cause mortality (adjusted odds ratio: 7.632; 95% CI: 2.244-25.961; p = 0.0011). Other significant and independent predictors for mortality included the hs-CRP level (every 100 microg/dl increase), hypertension and diabetes mellitus. CONCLUSIONS: Our findings suggest that the serum MBL level is a significant predictor of outcome in HD patients. HD patients with a low level of serum MBL should be carefully monitored.

Adult↗
PubMed2005

Human M-ficolin is a secretory protein that activates the lectin complement pathway.

Three types of ficolins have been identified in humans: L-ficolin, M-ficolin, and H-ficolin. Similar to mannose-binding lectin, L-ficolin and H-ficolin are the recognition molecules in the lectin complement pathway. Another human ficolin, M-ficolin, is a nonserum ficolin that is expressed in leukocytes and lung; however, little is known about its physiologic roles. In this study, we report the characterization of M-ficolin in terms of its protein localization and lectin activity. M-ficolin was localized in secretory granules in the cytoplasm of neutrophils, monocytes, and type II alveolar epithelial cells in lung. M-ficolin precipitated with mannose-binding lectin-associated serine proteases (MASP)-1 and MASP-2 in a co-immunoprecipitation assay, indicating that M-ficolin forms complexes with MASP-1 and MASP-2. M-ficolin-MASP complexes activated complement on N-acetylglucosamine (GlcNAc)-coated microplates in a C4 deposition assay. M-ficolin bound to several neoglycoproteins bearing GlcNAc, N-acetylgalactosamine, and sialyl-N-acetyllactosamine, suggesting that M-ficolin can recognize the common carbohydrate residues found in microbes. Indeed, M-ficolin bound to Staphylococcus aureus through GlcNAc. These results indicate that M-ficolin, like its family members, functions as a recognition molecule of the lectin complement pathway and plays an important role in innate immunity.

Complement Activation↗
PubMed2005

Polymorphisms in the FCN2 gene determine serum variation and function of Ficolin-2.

The ficolin 1, 2 and 3 (derived from the FCN1, 2 and 3 genes, respectively) are homologous soluble pattern recognition molecules of importance for innate immunity, comprising collagen-like and fibrinogen-like domains, binding to sugar groups on different types of microorganisms. Serum concentration of Ficolin-2 varies considerably in healthy individuals. Thus, we speculated whether this could be due to variations in the FCN2 gene. We sequenced the promoter region and the exons and intron-exon boundaries of FCN2 in Danish Caucasians. For comparison, FCN1 and FCN3 were also investigated. Ficolin-2 concentrations were measured in serum and the functional relevance of amino acid substituting polymorphisms in FCN2 was investigated by binding to and recovery from N-acetylglucosamine (GlcNAc). Both FCN1 and FCN2 contained polymorphisms in the promoters and structural parts of the genes, but only polymorphisms in FCN2 resulted in amino acid exchanges. FCN2 promoter polymorphisms were associated with marked changes in the Ficolin-2 serum concentration, whereas two polymorphisms clustered in the exon encoding the fibrinogen-like domain were associated with increased and decreased GlcNAc binding, respectively. In FCN3, only a single frame-shift deletion in exon 5 was detected. These results show that the FCN genes are polymorphic and that particularly FCN2 harbors functional polymorphic sites that regulate both the expression as well as the function of Ficolin-2, which may have pathophysiological implications for innate immunity.

Acetylglucosamine↗
PubMed2005

Ficolin A and ficolin B are expressed in distinct ontogenic patterns and cell types in the mouse.

Ficolins are a group of proteins characterized by the presence of collagen-like and fibrinogen-like domains. Two of three human ficolins, L-ficolin and H-ficolin, are serum lectins that form complexes with mannose-binding lectin-associated serine proteases (MASPs) and play important roles in the lectin complement pathway. The other human ficolin, M-ficolin, is a non-serum-type ficolin that is expressed in monocytes. Little is known about the physiological roles of ficolins. In this study, we delineated the ontogeny and cell types that express ficolins in mice. RT-PCR analysis showed that the expression pattern of ficolin A expression was closely similar to that of Masps, suggesting that these molecules may function in coordination as components of the lectin complement pathway. The cell types that express ficolin A mRNA in both adult liver and spleen were identified as macrophages by in situ hybridization. Ficolin B exhibited a distinct ontogeny pattern that switched from embryonic liver to postnatal bone marrow and spleen. The cells that express ficolin B mRNA were identified as belonging to the myeloid cell lineage by magnetic sorting and by subsequent RT-PCR in bone marrow cells. Thus, the different spatial-temporal expression patterns of ficolins A and B suggest that these molecules play distinct roles in the prenatal and postnatal stages.

Animals↗
PubMed2005

Role of L-ficolin/mannose-binding lectin-associated serine protease complexes in the opsonophagocytosis of type III group B streptococci.

Serotype III group B streptococci (GBS) are a common cause of neonatal sepsis and meningitis. Although deficiency in maternal capsular polysaccharide (CPS)-specific IgG correlates with susceptibility of neonates to the GBS infection, serum deficient in CPS-specific IgG mediates significant opsonophagocytosis. This IgG-independent opsonophagocytosis requires activation of the complement pathway, a process requiring the presence of both Ca(2+) and Mg(2+), and is significantly reduced by chelating Ca(2+) with EGTA. In these studies, we defined a role of L-ficolin/mannose-binding lectin-associated serine protease (MASP) complexes in Ca(2+)-dependent, Ab-independent opsonophagocytosis of serotype III GBS. Incubation of GBS with affinity-purified L-ficolin/MASP complexes and C1q-depleted serum deficient in CPS-specific Ab supported opsonophagocytic killing, and this killing was inhibited by fluid-phase N-acetylglucosamine, the ligand for L-ficolin. Binding of L-ficolin was proportional to the CPS content of individual strains, and opsonophagocytic killing and C4 activation were inhibited by fluid-phase CPS, suggesting that L-ficolin binds to CPS. Sialic acid is known to inhibit alternative complement pathway activation, and, as expected, the bactericidal index (percentage of bacteria killed) for individual strains was inversely proportional to the sialic acid content of the CPS, and L-ficolin-initiated opsonophagocytic killing was significantly increased by addition of CPS-specific IgG2, which increased activation of the alternative pathway. We conclude that binding of L-ficolin/MASP complexes to the CPS generates C3 convertase C4b2a, which deposits C3b on GBS. C3b deposited by this lectin pathway forms alternative pathway C3 convertase C3bBb whose activity is enhanced by CPS-specific IgG2, leading to increased opsonophagocytic killing by further deposition of C3b on the GBS.

Animals↗
PubMed2005

Specific binding of L-ficolin and H-ficolin to apoptotic cells leads to complement activation.

The serum lectins mannose-binding lectin (MBL), L-ficolin, and H-ficolin are recognition molecules in the lectin complement pathway, which play an important role in innate immunity. To assess involvement of the lectin pathway in the clearance of apoptotic cells, we used flow cytometry to quantify binding of MBL, L-ficolin, and H-ficolin to apoptotic HL60, U937, and Jurkat cells induced by actinomycin D. When apoptotic cells were incubated with normal human serum, MBL and L-ficolin bound to all three cell lines tested; moreover, H-ficolin bound to apoptotic Jurkat cells only. Subsequently, C4 and C3 were deposited on apoptotic cells of all three cell lines. MBL, L-ficolin, and H-ficolin binding to apoptotic cells was confirmed by the use of purified proteins. Purified C4 added to apoptotic cells that had bound pure L-ficolin was deposited on the cell surfaces. In L-ficolin-depleted serum, C3 deposition on HL60 or Jurkat cells decreased to approximately 50% or 70%, respectively, in comparison to the serum before L-ficolin depletion. We conclude that L-ficolin, in addition to MBL, recognizes apoptotic cells and activates complement via the lectin pathway. We also observed in vitro binding of L-ficolin and H-ficolin to cC1q receptor (C1q receptor specific for the collagenous region of C1q)/calreticulin, a candidate receptor for the collagenous region of MBL and C1q. Thus, L-ficolin and H-ficolin as well as MBL participate in the clearance of apoptotic cells through complement activation.

Apoptosis↗
PubMed2005

Activation of the lectin complement pathway in Henoch-Schönlein purpura nephritis.

BACKGROUND: We previously reported the existence of complement activation through the alternative and lectin pathways in patients with immunoglobulin A (IgA) glomerulonephritis (GN). The current study aims to elucidate the correlation between each complement pathway and clinicopathologic findings in patients with Henoch-Schonlein purpura nephritis (HSPN). METHODS: Immunohistologic staining was performed on renal specimens obtained from 31 patients with HSPN and 20 controls as non-IgA GN by using antibodies against IgG, IgA, IgA1, IgA2, IgM, C1q, C3c, C4, fibrinogen, factor B, C4-binding protein (C4-bp), C5b-9, CD59, mannose-binding lectin (MBL), and MBL-associated serine protease-1 (MASP-1). RESULTS: No control showed deposition of any antibody. In 16 patients with mesangial IgA1/IgA2 codeposits, mesangial deposits of C3c, C4, factor B, C4-bp, C5b-9, CD59, MBL, and MASP-1 were found. In the remaining 15 patients with mesangial IgA1 deposits alone, no mesangial deposits of C4 or MBL/MASP-1 were found, and mesangial deposits of C3c, factor B, C5b-9, and CD59 were evident in 11 patients. Glomerular deposits of fibrinogen were detected in 15 of 16 patients with IgA1/IgA2 codeposits and only 6 of 15 patients with IgA1 deposits. Severity of glomerular changes and degrees of hematuria and proteinuria at latest follow-up were greater in patients with IgA1/IgA2 codeposits than in those with IgA1 deposits. CONCLUSION: Complement activation through both the alternative and lectin pathways is found in patients with HSPN. Complement activation is promoted in situ in the glomerulus. MBL/MASP-1 may be associated with glomerular deposition of fibrinogen. Complement activation through the lectin pathway may contribute to the development of advanced glomerular injuries and prolonged urinary abnormalities in patients with HSPN.

Adolescent↗
PubMed2005

Stool decay-accelerating factor as a marker for monitoring the disease activity during leukocyte apheresis therapy in patients with refractory ulcerative colitis.

BACKGROUND AND AIMS: We have shown previously that concentrations of stool decay-accelerating factor (DAF; CD55), a complement regulatory protein, in patients with ulcerative colitis (UC) are increased in relation to the severity of the colonic mucosal inflammation. In the present study, we evaluated the usefulness of stool DAF as a marker for monitoring disease activity in patients with steroid-resistant active UC being treated with leukocyte apheresis performed with a centrifugal cell separator. METHODS: Twenty-one patients with active and steroid-resistant UC were treated with leukocyte apheresis once a week for 4 weeks, and stool DAF concentrations were determined weekly by immunoassay. RESULTS: After treatment, 11 (52%) of the 21 UC patients went into remission. Stool DAF concentrations decreased promptly and steadily in the responsive group. The difference reached statistical significance as soon as after the second apheresis session (P < 0.003), compared with values before the therapy and corresponding values in the non-responsive group (P = 0.024). The reduction in stool DAF concentrations after the second apheresis session was significantly greater in the responsive group (median 90%, range 22-90%) than in the non-responsive group (median -13%, range -307-94%) (P = 0.008). Hematological tests, that is, white blood cell (WBC) count and C-reactive protein, declined significantly during the apheresis therapy, but not in relation to therapeutic response. CONCLUSION: Stool DAF concentration is a useful marker in the clinical response of UC patients to treatment with leukocyte apheresis.

Adolescent↗
PubMed2005

Association between mannose-binding lectin levels and graft survival in kidney transplantation.

The mannose-binding lectin (MBL) pathway of complement is activated by pattern recognition. Genetic MBL variants are frequent and associated with low MBL serum levels. Higher MBL levels may be associated with more complement-mediated damage resulting in inferior graft survival. Pre-transplant serum samples from 266 consecutive deceased donor kidney transplant recipients were analyzed for MBL concentration by ELISA. Subsequently the cohort was analyzed for transplant-related outcome. There was no significant difference in incidence of delayed graft function in recipients with a low MBL level (< or =400 ng/mL) compared to those with a higher MBL level (>400 ng/mL) (37.1 vs. 34.9%). At 10 years, death-censored graft survival was 89.9% in patients with an MBL level below 400 ng/mL compared with 78.8% at a higher MBL level (p < 0.02). Multivariate analysis including traditional risk factors for graft loss showed an independent risk of 2.7 (95% CI 1.2-6.3) for death-censored graft loss if pre-transplant MBL levels were above 400 ng/mL. This difference was almost entirely explained by rejection-associated graft loss (2.4 vs. 12.4%, p < 0.01). Higher MBL levels seem to be associated with a more severe form of rejection leading to treatment failure and graft loss. If these data can be confirmed, pre-transplant MBL levels may provide additional information for risk stratification prior to kidney transplantation.

Adult↗
PubMed2005

Production and purification of recombinants of mouse MASP-2 and sMAP.

Small mannose-binding lectin (MBL)-associated protein (sMAP) is a component of the complex consisting of MBL and MBL-associated serine proteases (MASPs) in the lectin complement pathway. sMAP is a truncated form of MASP-2, which is generated by an alternative splicing from a single structural MASP-2 gene. Upon activation of the MBL-MASPs complex, MASP-2 cleaves the complement C4, but the role of sMAP which lacks the serine protease domain is not clear. To clarify the role of sMAP in activation of the lectin pathway, we have generated sMAP-gene deficient mice which are also deficient for MASP-2. In this study, we generated and purified mouse recombinant sMAP (rsMAP) and rMASP-2 using the Drosophila expression system for the reconstitution assay of the deficient mice. In preliminary experiments, these purified recombinants were able to reconstitute the MBL-MASPs-sMAP complexes and the addition of rMASP-2 to deficient serum restored the C4 cleavage activity of the MBL-MASPs complex. From these data, rsMAP and rMASP-2 generated in this study seem to be useful in analysis of the deficient mice.

Alternative Splicing↗
PubMed2004

The CC chemokine receptor 4 as a novel specific molecular target for immunotherapy in adult T-Cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell neoplasm with dismal prognosis, and no optimal therapy has been developed. We tested the defucosylated chimeric anti-CC chemokine receptor 4 (CCR4) monoclonal antibody, KM2760, to develop a novel immunotherapy for this refractory tumor. In the presence of peripheral blood mononuclear cells (PBMCs) from healthy adult donors, KM2760 induced CCR4-specific antibody-dependent cellular cytotoxicity (ADCC) against CCR4-positive ATLL cell lines and primary tumor cells obtained from ATLL patients. We next examined the KM2760-induced ADCC against primary ATLL cells in an autologous setting. Antibody-dependent cellular cytotoxicity mediated by autologous effector cells was generally lower than that mediated by allogeneic control effector cells. However, a robust ADCC activity was induced in some cases, which was comparable with that mediated by allogeneic effector cells. It suggests that the ATLL patients' PBMCs retain substantial ADCC-effector function, although the optimal conditions for maximal effect have not yet been determined. In addition, we also found a high expression of FoxP3 mRNA and protein, a hallmark of regulatory T cells, in ATLL cells, indicating the possibility that ATLL cells originated from regulatory T cells. KM2760 reduced FoxP3 mRNA expression in normal PBMCs along with CCR4 mRNA by lysis of CCR4+ T cells in vitro. Our data suggest not only that the CCR4 molecule could be a suitable target for the novel antibody-based therapy for patients with ATLL but also that KM2760 may induce effective tumor immunity by reducing the number of regulatory T cells.

Antibodies, Monoclonal↗