To cite this article: Lancellotti S, De Filippis V, Pozzi N, Oggianu L, Rutella S, Scaglione GL, Maset F, Peyvandi F, Mannucci PM, De Cristofaro R. Oxidized von Willebrand factor is efficiently ...cleaved by serine proteases from primary granules of leukocytes: divergence from ADAMTS‐13. J Thromb Haemost 2011; 9: 1620–7.
Summary. Background: The leukocyte serine proteases (LSPs) elastase, proteinase 3 and cathepsin G cleave von Willebrand factor (VWF) near or at the same cleavage site (Tyr1605–Met1606) as ADAMTS‐13, the metalloprotease that specifically controls the proteolytic processing of VWF. Recent studies have shown that oxidation of VWF at Met1606 with formation of methionine sulfoxide (MetSO) severely impairs its proteolysis by ADAMTS‐13. Methods: This study was aimed at assessing whether or not oxidation of VWF by reactive oxygen species (ROS) can also affect its cleavage by elastase, proteinase 3, and cathepsin G. In this study, the catalytic specificity of hydrolysis by LSPs of the VWF peptide substrate VWF74 and full‐length VWF, both unaltered and in the oxidized form, was measured by RP‐HPLC, electrophoretic and mass spectrometry methods. Results: LSPs cleaved both VWF multimers and VWF74 near or at the same peptide bond as is cleaved by ADAMTS‐13, with kcat/Km values similar to those of the metalloprotease. However, unlike ADAMTS‐13, cathepsin G cleaved VWF74 containing a MetSO residue at position 1606 with a kcat/Km value higher than that for VWF74, whereas the catalytic efficiencies of both elastase and proteinase 3 were unaffected by the replacement of Met1606 with MetSO. Likewise, oxidation of VWF multimers by hypochlorous acid and ROS, produced by activated leukocytes, improved their hydrolysis by LSPs. Conclusions: Oxidation by leukocyte ROS has a net positive effect on the cleavage of VWF multimers by LSPs, under conditions where high concentrations of oxidant species would severely reduce the proteolytic efficiency of ADAMTS‐13.
Abstract Recent efforts have been directed toward new therapeutic options to approach drug-induced hepatitis. We report a case of acute liver failure associated with Nimesulide in a 67-year-old man, ...with a medical history of chronic alcohol abuse. The biopsy was compatible with chronic alcoholic liver disease and acute drug-induced injury. The patient was enrolled to receive G-CSF followed by aphaeresis and selection of peripheral-blood stem cells. After ultrasound-guided injection of CD34+cells in the portal vein, we observed a rapid improvement of synthetic liver function, with particular reference to coagulation parameters. Liver biopsy performed 20 days after, showed wide areas of regeneration. In the next 30 days the laboratory signs of acute decompensation progressively improved. Unfortunately he died of multiple-organ failure related to bacterial infection. Intrahepatic injection of peripheral-blood stem cells seemed safe and produced good periprocedural results with improvement of synthetic profile, suggesting a possible role of stem cells in the regeneration process.
Summary Background Literature data report an association between some vitamin D receptor (VDR) polymorphisms and different kinds of tumours, including malignant melanoma (MM). Only three VDR ...polymorphisms (FokI, TaqI and A‐1012G) have been investigated in association with the presence of cutaneous MM or the development of metastases.
Objectives The present paper analyses for the first time the association between BsmI polymorphism and MM prevalence together with Breslow thickness. In addition, the FokI single nucleotide polymorphism was also determined.
Methods One hundred and one patients with MM and 101 healthy donors matched for age and sex were enrolled. Molecular VDR typing was performed by means of restriction fragment length polymorphism analysis.
Results All cases and controls were in Hardy–Weinberg equilibrium for BsmI, FokI and A‐1012G. Significant associations were found between the BsmI bb genotype frequency and MM (P = 0·02) along with Breslow thickness (P = 0·001). This same behaviour was not observed for the FokI or A‐1012G polymorphisms. Multivariate logistic regression analysis confirmed these significant results after correction for age, gender, skin type and MM localization.
Conclusions Although the biological meaning of the effects exerted by BsmI polymorphism is still under debate, the statistical association found in the present study suggests that further work should be done to verify this variant as a possible risk marker for MM and its aggressiveness, also considering that the real association may be due to other unknown genes linked to the BsmI b allele.
Gemtuzumab ozogamicin (GO) is effective as single agent in the treatment of acute myeloid leukemia (AML). We evaluated efficacy and safety of a chemotherapy including growth factors, cytarabine, and ...GO (G-AraMy) in the treatment of poor-prognosis AML in elderly patients.
In three Italian hematology departments from September 2003 to September 2006, 53 elderly patients median age 69 years (range 65-77) with untreated or primary refractory/relapsed AML were enrolled on the combination G-AraMy administered according to two consecutive schedules (G-AraMy1 and G-AraMy2), with intensified consolidation in the second. Twenty-three of 53 patients had a secondary acute myeloid leukemia (sAML).
The overall response rate was 57%. The most common adverse event was myelosuppression. Seven patients died in induction (13%). No differences for response rate and toxicity profile were observed between untreated and primary resistant/relapsed patients, de novo AML and sAML, and in the two treatment trials. Median disease-free survival and overall survival were 8 months (range 2-23+) and 9 months (range 2-24+).
G-AraMy therapy may be considered an useful treatment approach for poor-risk elderly AML patients, with a complete remission rate comparable to literature data with reduced side-effects, also in a poor-prognosis population.
The enzyme indoleamine 2,3-dioxygenase (IDO) regulates immune responses through the capacity to degrade the essential amino acid tryptophan into kynurenine and other downstream metabolites that ...suppress effector T-cell function and favour the differentiation of regulatory T cells. Considerable experimental evidence indicates that IDO can be expressed by dendritic cells, by tumour cells or by surrounding stromal cells, either within proximity of the tumour or at distal sites. Recent advances in the biochemistry of IDO and in our understanding of the biological relevance of IDO-mediated tryptophan consumption to the establishment of dominant immune tolerance to cancer will be summarised and discussed. Within the wider context of cancer immunotherapy, this Review also delineates how IDO could be exploited as a molecular target for therapeutic intervention in order to boost anti-cancer immunity.
Background: We report a novel case of gray platelet syndrome (GPS). A 14‐year‐old boy had bleeding diathesis, mild thrombocytopenia, giant platelets with severe defect of α‐granule secretory ...proteins, myelofibrosis and splenomegaly. Methods and results: Platelet function studies showed a marked reduction of aggregation and Ca2+ mobilization by thrombin, protease‐activated receptor 1 (PAR1)‐activating peptide (AP) and PAR4‐AP, PAR1 expression at 55% of normal levels, and a more than two hundred fold reduction of in vitro whole‐blood thromboxane B2 (TXB2) production. Sequencing of coding regions of the PAR1 gene failed to show abnormalities. This patient was initially classified as a sporadic case of GPS, as electron microscopy failed to identify giant platelets and/or α‐granule deficiency in his relatives. However, further studies on the father and three other relatives showed a relative lack of platelet α‐granule proteins by immunofluorescence microscopy, a defective platelet response to PAR4‐AP, and severely reduced in vitro whole‐blood TXB2 production. On this basis, we suggest that in this family, GPS was transmitted in a dominant fashion with highly variable penetrance. Conclusions: Our study suggests that current diagnostic criteria fail to identify some patients with a mild GPS phenotype and that such patients might be identified by the methods cited above. It also better characterizes the pathogenesis of defective platelet responses to thrombin, and raises interesting questions on the correlation between abnormal PAR function and the lack of α‐granule content in GPS.
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