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Congenital macrothrombocytopenia is a genetically heterogeneous group of rare disorders. αIIbβ3 has not been implicated in these conditions. We identified a novel, conserved heterozygous ITGA2B R995W mutation in 4 unrelated families. The surface expression of platelet αIIbβ3 was decreased to 50% to 70% of control. There was spontaneous PAC-1 and fibrinogen binding to resting platelets without CD62p expression. The activation state of αIIbβ3 in 293T cells was higher for αIIb-W995 than for β3-H723 but was weaker than for β3-N562. FAK was spontaneously phosphorylated in αIIb-W995/β3-transfected 293T cells. These results indicate that αIIb-W995/β3 has a constitutive, activated conformation but does not induce platelet activation. αIIb-W995/β3-transfected CHO cells developed membrane ruffling and abnormal cytoplasmic protrusions. The increased size and decreased number of proplatelet tips in αIIb-W995/β3-transduced mouse fetal liver-derived megakaryocytes indicate defective pro-platelet formation. We propose that activating mutations in ITGA2B and ITGB3 represent the etiology of a subset of congenital macrothrombocytopenias.

NK cells are innate immune lymphocytes and play a key role in both innate and adaptive immunity. Their pivotal functions in vivo have been illustrated in mice by means of their ablation with NK cell-depleting Abs, particularly anti-asialo GM1 (ASGM1). In this study, we show that the whole population of basophils constitutively expresses ASGM1 as well as CD49b (DX5) as does the NK cell population and was ablated in vivo by anti-ASGM1 as efficiently as by a basophil-depleting anti-FcεRIα Ab. Anti-ASGM1-mediated basophil depletion was operative as for NK cell depletion in various mouse strains, irrespective of NK1 allotype and MHC H2 haplotype, including C57BL/6, BALB/c, C3H, and A/J mice. These results identified basophils as a previously unrecognized target of anti-ASGM1-mediated cell depletion and raised concern about possible contribution of basophils, rather than or in addition to NK cells, to some of phenotypes observed in anti-ASGM1-treated mice. Indeed, regardless of the presence or absence of NK cells in mice, anti-ASGM1 treatment abolished the development of IgE-mediated chronic cutaneous allergic inflammation as efficiently as did the treatment with basophil-depleting Ab. Given the fact that basophils have recently been shown to play crucial roles in a variety of immune responses, our finding of the off-target effect on basophils issues a grave warning about the use of anti-ASGM1 and underscores the need for careful interpretation of phenotypes observed in anti-ASGM1-treated mice.

Snail transcription factor induces epithelial-mesenchymal transition (EMT) in which the epithelial cells downregulate cell-cell adhesion genes such as E-Cadherin and upregulate mesenchymal genes such as vimentin, leading to increased invasion and migration. Very little is known about the role of Snail in cellular adhesion to the extracellular matrix. We hypothesized that Snail will lead to decreased cellular adhesion to fibronectin and collagen I matrix through integrin regulation, concomitant with increased cell migration. Androgen-independent C4-2 cells, an aggressive subline of androgen-dependent LNCaP cells, exhibited decreased cell adhesion and increased cell migration on fibronectin and collagen I as compared to LNCaP cells, which was reversed by Snail knock down in C4-2 cells. ARCaP and LNCaP prostate cancer cells stably transfected with Snail displayed decreased adhesion and increased cell migration on fibronectin and collagen I as compared to control Neo-transfected cells, which was reversed by Snail knockdown. Flow cytometry analysis revealed a decrease in a5, a2 and b1 integrin expression in ARCaP Snail-transfected cells that was reversed in Snail knock down cells. We also observed an increase in ERK phosphorylation in ARCaP Snail-transfected cells as compared to control ARCaP-Neo cells, and inhibition of the MAPK pathway with UO126 inhibitor in ARCaP Snail-transfected cells abrogated Snail-mediated decrease in cell adhesion and reinduced a5, a2 and b1 integrin expression. Collectively, these studies define a new role for Snail transcription factor in cell adhesion to the ECM, which may be mediated by MAPK signaling, and may be crucial for cell detachment and subsequent metastasis.

Leukocyte adhesion deficiency type III is a recently described condition involving a Glanzmann-type bleeding syndrome and leukocyte adhesion deficiency. This was ascribed to a defect of the FERMT3 gene resulting in abnormal expression of kindlin-3, a protein expressed in hematopoietic cells with a major role in the regulation of integrin activation. In this article, we describe a patient with a new mutation of FERMT3 and lack of kindlin-3 expression in platelets and leukocytes. We assayed quantitatively the first steps of kindlin-3-defective leukocyte adhesion, namely, initial bond formation, bond strengthening, and early spreading. Initial bond formation was readily stimulated with neutrophils stimulated by fMLF, and neutrophils and lymphocytes stimulated by a phorbol ester or Mn(2+). In contrast, attachment strengthening was defective in the patient's lymphocytes treated with PMA or Mn(2+), or fMLF-stimulated neutrophils. However, attachment strengthening was normal in patient's neutrophils treated with phorbol ester or Mn(2+). In addition, the patient's T lymphocytes displayed defective integrin-mediated spreading and a moderate but significant decrease of spreading on anti-CD3-coated surfaces. Patient's neutrophils displayed a drastic alteration of integrin-mediated spreading after fMLF or PMA stimulation, whereas signaling-independent Mn(2+) allowed significant spreading. In conclusion, the consequences of kindlin-3 deficiency on β(2) integrin function depend on both cell type and the stimulus used for integrin activation. Our results suggest looking for a possible kindlin-3 involvement in membrane dynamical event independent of integrin-mediated adhesion.

Background: Integrins influence tumourigenesis, tumor progression and development of metastases. The impact of polymorphisms in integrin genes on relapse-free survival (RFS) and overall survival (OS) for 433 Caucasian patients with colorectal cancer was analysed in this retrospective study., Patients and Methods: A Cox regression model including integrin genotype, age, grading, tumour size, number of lymph nodes examined, number of metastatic lymph nodes, stage and application of fluorouracil-based adjuvant chemotherapy was used to estimate their effect., Results: After a median follow-up of 41 months for RFS and 55 months for OS, no significant correlation between the ITGA2 1648A allele (RFS p=0.618, OS p=0.604), the ITGA2 807T allele (RFS p=0.603, OS p=0.807) and the ITGB3 176C allele (RFS p=0.719, OS p=0.261) and survival was detectable., Conclusion: The investigated integrin polymorphisms are not associated with RFS or OS in colorectal cancer patients.

Mesenchymal stem cells (MSCs) cultured on extracellular matrices with different stiffness have been shown to possess diverse lineage commitment owing to the extracellular mechanical stimuli sensed by the cells. The aim of this study was to further delineate how matrix stiffness affects intracellular signaling through the mechanotransducers Rho kinase (ROCK) and focal adhesion kinase (FAK) and subsequently regulates the osteogenic phenotype of MSCs. MSCs were cultured in osteogenic medium on tunable polyacrylamide hydrogels coated with type I collagen with elasticities corresponding to Young's modulus of 7.0 ± 1.2 and 42.1 ± 3.2 kPa. Osteogenic differentiation was increased on stiffer matrices, as evident by type I collagen, osteocalcin, and Runx2 gene expressions and alizarin red S staining for mineralization. Western blot analysis demonstrated an increase in kinase activities of ROCK, FAK, and ERK1/2 on stiffer matrices. Inhibition of FAK, an important mediator of osteogenic differentiation, and inhibition of ROCK, a known mechanotransducer of matrix stiffness during osteogenesis, resulted in decreased expression of osteogenic markers during osteogenic induction. In addition, FAK affects osteogenic differentiation through ERK1/2, whereas ROCK regulates both FAK and ERK1/2. Furthermore, α(2)-integrin was upregulated on stiffer matrices during osteogenic induction, and its knockdown by siRNA downregulated the osteogenic phenotype through ROCK, FAK, and ERK1/2. Taken together, our results provide evidence that the matrix rigidity affects the osteogenic outcome of MSCs through mechanotransduction events that are mediated by α(2)-integrin., (Copyright © 2011 American Society for Bone and Mineral Research.)

Objective: Ischemic stroke is prevalent in type 2 diabetes and may be due to metabolic, vascular and inflammatory factors. Genetic variants implicated in these pathways may have joint effects on stroke risk. In this proof-of-concept study, we examined gene-gene interactions on risk of incident ischemic stroke in an 8-year prospective cohort of Chinese type 2 diabetic patients., Methods: Seventy-seven single nucleotide polymorphisms (SNPs) of 53 candidate genes for cardiovascular disease and inflammation were genotyped in 1327 patients with no past history of ischemic stroke. The association of SNPs with stroke was tested using Cox proportional hazard regression analysis. Permutation procedure was performed to control for multiple statistical comparisons., Results: Genetic variants including A/A of IL5RA (interleukin-5 alpha subunit) -5091G>A, X/X of LPL (lipoprotein lipase) S447X, A/A of ITGA2 (integrin A2) G873A and T/T or G/T of NOS3 (endothelial nitric oxide synthase) G894T showed significant correlations with incident ischemic stroke. The hazard ratios (HR) increased with number of genetic risk factors reaching an adjusted HR (confidence interval) of 3.68 (1.78-7.62, P=4.4×10(-4)) in those with ≥2 genetic risk factors compared to those without., Conclusion: Polymorphisms in IL5RA, LPL, ITGA2 and NOS3 genes were independently associated with ischemic stroke in Chinese diabetic population., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Unlike skin, oral gingiva do not scar in response to injury. The basis of this difference is likely to be revealed by comparing the responses of dermal and gingival fibroblasts to fibrogenic stimuli. Previously, we showed that, compared to dermal fibroblasts, gingival fibroblasts are less responsive to the potent pro-fibrotic cytokine TGFβ, due to a reduced production of endothelin-1 (ET-1). In this report, we show that, compared to dermal fibroblasts, human gingival fibroblasts show reduced expression of pro-adhesive mRNAs and proteins including integrins α2 and α4 and focal adhesion kinase (FAK). Consistent with these observations, gingival fibroblasts are less able to adhere to and spread on both fibronectin and type I collagen. Moreover, the enhanced production of ET-1 mRNA and protein in dermal fibroblasts is reduced by the FAK/src inhibitor PP2. Given our previous observations suggesting that fibrotic fibroblasts display elevated adhesive properties, our data suggest that scarring potential may be based, at least in part, on differences in adhesive properties among fibroblasts resident in connective tissue. Controlling adhesive properties may be of benefit in controlling scarring in response to tissue injury.

The functional effect of platelet membrane glycoprotein Ia (GPIa) gene 807C/T polymorphism in unstable angina pectoris (UAP) pathogenesis was investigated in Chinese Han individuals. Collagen type I-induced platelet aggregation was measured in 33 healthy subjects. Plasma levels of α-granule membrane protein (GMP-140) were measured in 33 healthy subjects and in 35 patients with recent-onset angina at rest within 24 h of hospitalization. Platelet membrane GPIa gene 807C/T polymorphism was determined in all subjects. Lag-time before 30% platelet aggregation was significantly longer in CC genotype than in TC genotype healthy subjects, although there was no significant difference in maximal platelet aggregation between healthy subjects with either genotype. Plasma GMP-140 levels were significantly higher in TC genotype patients compared with CC genotype patients or healthy subjects; a significant difference was also observed between the latter two groups. It was concluded that rapid initiation of collagen-induced platelet aggregation may be associated with the platelet membrane GPIa T807 allele, which may be important in UAP pathogenesis.

Purpose: The aim of this study was to identify the presence of collagen-binding integrin subunits in human scleral fibroblasts (HSFs) and investigate their actual functions in maintaining the mechanical creep properties of the HSFs-seeded collagen matrix., Methods: Primary HSFs were cultured in vitro. Reverse- transcription PCR was used to detect mRNA expression of integrin α1, α2, and β1 subunits in HSFs. In addition, western blot analysis and immunofluorescence were used to detect their protein in HSFs. Monoclonal antibodies were applied directly against the extracellular domains of integrin subunits in HSFs cultured in the three-dimensional collagen gels to block the interaction between HSFs and the extracellular collagen matrix. The effects of anti-integrin antibodies on HSFs morphology in collagen gel were observed. The effects of the added antibodies on fibroblast-mediated collagen gels' contraction were evaluated. Furthermore, the changes in mechanical creep properties of collagen gel were measured by a biomechanics test instrument., Results: The mRNA and protein expressions of collagen-binding integrin α1, α2, and β1 subunits were present in HSFs. The elongated bipolar cells converted to spherical shapes after 6 h after the addition of integrin α1β1 and α2β1 antibody. The blocking of integrin α1β1 and α2β1 subunits noticeably decreased the contraction in the collagen gels. In addition, all samples were subjected to a constantly applied load of 0.03 N for 600 s. The blocking of integrin α1β1 and α2β1 subunits also induced increases in the values of final extension, creep extension, and creep rate, compared to those of the controls (p<0.01). Furthermore, the creep elements were significantly increased with the augmentation of the integrin antibody dose (p<0.01). The final extension of the integrin α2β1 antibody (1 μg/ml or 4 μg/ml) group was significantly higher compared to that of the integrin α1β1 antibody (1 μg/ml or 4 μg/ml) group (p<0.01). However, the creep extension and creep rate of the integrin α2β1 antibody (1 μg/ml or 4 μg/ml) group were not significantly different from those in the integrin α1β1 antibody (1 μg/ml or 4 μg/ml) group (p>0.05)., Conclusions: Our findings suggested that HSF integrin α1β1 and α2β1 participated in maintaining the mechanical creep properties of the HSFs-seeded collagen matrix. Furthermore, integrin α2β1 might play a more crucial role in maintaining the mechanical creep properties of the collagen matrix than does integrin α1β1.

The question as to whether Glanzmann thrombasthenia patients with ITGB3 defects and deficiencies of both αIIbβ3 and αvβ3 show phenotypic differences to those with abnormalities exclusive to αIIbβ3 is unresolved. Studies on β3-deficient mice have shown an increased bone mass. Here we review the literature on bone defects in thrombasthenia patients and report the molecular analysis of a patient associating a lifelong thrombasthenia-like syndrome with skeletal defects. We show that the patient is compound heterozygote for Arg327His and Gly391Arg mutations in αIIb, with one mutation inherited from each parent. Modelling strongly suggested that both mutations act by destabilizing the αIIb beta propeller. So it appears likely that this patient has a combination of co-expressed genetic defects.

Purpose: This phase I study was conducted to characterize the safety profile, pharmacokinetics, pharmacodynamics, dose-limiting toxicity (DLT), and the maximum-tolerated dose of E7820, a novel oral sulfonamide derivative with antiangiogenic properties, when administered to patients with advanced solid malignancies., Patients and Methods: Patients received single daily doses of E7820 orally for 28 days in cycle 1, followed by a 7-day no-treatment period, after which time-uninterrupted daily dosing ensued. The starting dose of E7820 was 10 mg/d, which was increased to 20, 40, 70, 100, and 200 mg/d in cohorts of new patients., Results: Thirty-seven patients [21 male; median age 65 (40-82] were enrolled. At 100 mg/d, 1 patient experienced a DLT consisting of grade 3 neutropenia, thrombocytopenia, and elevated liver enzymes. At the 200-mg dose level, 2 patients experienced grade 4 thrombocytopenia and neutropenia. No partial or complete responses were observed; 8 patients had stable disease (≥ 4 months), including 5 patients with protracted stable disease exceeding 6 months. Mean time to maximum plasma concentration values ranged from 1 to 12 hours, whereas mean terminal half-life values ranged from 5.6 to 8.6 hours. Flow cytometric analysis of platelet integrin α-2 expression showed a sustained greater than 50% decrease beyond day 28 in 3 of 4 patients at 200 mg, whereas moderate (<30%) decreases were observed at 70- and 100-mg dose levels., Conclusions: The recommended phase II dose of E7820 is 100 mg/d, based on a fasting schedule. E7820 downregulates integrin α-2 expression in surrogate tissues (platelets) and is associated with stable disease in a wide variety of heavily pretreated malignancies., (©2011 AACR.)

Background: Studies of Glanzmann thrombasthenia (GT)-causing mutations has generated invaluable information on the formation and function of integrin αIIbβ(3)., Objective: To characterize the mutation in four siblings of an Israeli Arab family affected by GT, and to analyze the relationships between the mutant protein structure and its function using artificial mutations., Methods and Results: Sequencing disclosed a new A97G transversion in the αIIb gene predicting Asn2Asp substitution at blade 1 of the β-propeller. Alignment with other integrin α subunits revealed that Asn2 is highly conserved. No surface expression of αIIbβ(3) was found in patients' platelets and baby hamster kidney (BHK) cells transfected with mutated αIIb and WT β(3). Although the αIIbβ(3) was formed, the mutation impaired its intracellular trafficking. Molecular dynamics simulations and modeling of the αIIbβ(3) crystal indicated that the Asn2Asp mutation disrupts a hydrogen bond between Asn2 and Leu366 of a calcium binding domain in blade 6, thereby impairing calcium binding that is essential for intracellular trafficking of αIIbβ(3). Substitution of Asn2 to uncharged Ala or Gln partially decreased αIIbβ(3) surface expression, while substitution by negatively or positively charged residues completely abolished surface expression. Unlike αIIbβ(3), αVβ(3) harboring the Asn2Asp mutation was surface expressed by transfected BHK cells, which is consistent with the known lower sensitivity of αVβ(3) to calcium chelation compared with αIIbβ(3)., Conclusion: The new GT causing mutation highlights the importance of calcium binding domains in the β-propeller for intracellular trafficking of αIIbβ(3). The mechanism by which the mutation exerts its deleterious effect was elucidated by molecular dynamics., (© 2010 International Society on Thrombosis and Haemostasis.)

Immune thrombocytopenic purpura (ITP) is an autoimmune disease characterized by the presence of autoantibodies developing against thrombocyte membrane glycoproteins (GPs), such as GPIIa/IIIa and GPIb/IX. Single nucleotide polymorphisms (SNPs) of inflammatory cytokine genes were investigated in 71 patients with chronic ITP and 71 healthy controls, and they were compared with the clinical parameters. The polymorphisms in the SNPs were investigated with the polymerase chain reaction, polymerase chain reaction with sequence specific primer, and polymerase chain reaction-restriction fragment length polymorphism methods. It was found that the high expression of TNF-alpha (-308) AG phenotype significantly increased in cases with ITP (odds ratio, OR: 0.318, 95% confidence intervals, CI: 0.103-0.987, p < 0.05). TT genotype in TGF-beta 1 (codon 10) significantly decreased in ITP in comparison with the controls (OR: 0.342, 95% CI: 0.149-0.787, p = 0.016). IFN-gamma (+874) TT genotype was detected to be high in cases with ITP (OR: 3.301, 95% CI: 1.400-7.784, p < 0.05), whereas AA genotype was found to be significantly lower (OR: 4.993, 95% CI: 1.586-15.721, p < 0.05). MBL (codon 54) BB genotype (OR: 1.164, 95% CI: 1.059-1.279, p < 0.05) and IL1A A1/A2 genotype (OR: 0.249, 95% CI: 0.076-0.815, p < 0.05) were found to be significantly higher in cases with ITP than in healthy controls. TNF-alpha (-308) AG phenotype was detected to be significantly higher in steroid-refractory and splenectomized cases at the end of the first year than in the steroid-responsive (complete response (CR) and remission (R)) cases (OR: 4.137, 95% CI: 1.156-14.807, p < 0.05). When we compared the cases, from whom we obtained a CR at their first steroid response, with 12 cases, who entered R but from whom we could not obtain any CR, the frequencies of IFN-gamma (+874) AA genotype were found as 12 (20.3%) and 6 (50%) (OR: 0.082, 95% CI: 0.009-0.793, p < 0.05). MBL (codon 54) AB genotype was detected to be significantly higher in CR patients than in R cases (OR: 1.273, 95% CI: 1.110-1.459, p < 0.05). With these findings, it was found that TNF-alpha/AG, TGF-beta 1/TT, IFN-gamma/TT, MBL/BB, and IL-1RA A1/A2 genotypes were detected as the genes of susceptibility to ITP, while TNF-alpha/AG, IFN-gamma/AA, and MBL/AB genotypes might be important in response to steroid treatment.

History of thrombosis and polymorphisms of genes of hemocoagulation system were studied in 27 children with ischemic stroke. The distribution of allelic variants in the Russian population was compared to that in other world populations. Each patient had 4 and more allelic variants of hemocoagulation's genes. The most frequent were polymorphisms G-455A FGB, C807T ITGA2 and 675 4G4G PAI-1. Thrombotic episodes and vascular events under the age of 50 were noted in the family history of 81.5% patients. The modern data on frequencies of hemocoagulation gene polymorphisms in clinical and non-clinical populations of children and their phenotypic features are analyzed.

Cardiovascular diseases, including acute coronary syndrome (ACS), are the leading cause of death among humans. Adhesion proteins, owing to their involvement in the initiation and progression of atherosclerotic lesions, contribute to the progression of coronary disease and ACS occurrence. Considering ambiguosity of results reported to date, we decided to conduct a preliminary investigation of adhesion protein gene expression in ACS patients as well as in healthy subjects by making use of oligonucleotide microarray technology. Analysis of eight microarrays revealed ten upregulated genes differentiating between the two groups: intercellular adhesion molecule-2, platelet/endothelial cell adhesion molecule-1, zyxin, integrin-linked kinase, calcium and integrin binding protein-1 (calmyrin), integrin beta 2, integrin beta 3 (ITGB3), integrin beta 7, integrin alpha 2b, and selectin P ligand. The expression of ITGB3 was found to have been downregulated.

Collagen is an extracellular matrix structural component that can regulate cellular processes through its interaction with the integrins, α1β1, α2β1, α10β1, and α11β1. Collagen-like proteins have been identified in a number of bacterial species. Here, we used Scl2 from Streptococcus pyogenes serotype M28 strain MGAS6274 as a backbone for the introduction of discrete integrin-binding sequences. The introduced sequences GLPGER, GFPGER, or GFPGEN did not affect triple helix stability of the Scl (Streptococcal collagen-like) protein. Using ELISA and surface plasmon resonance, we determined that Scl2(GLPGER) and Scl2(GFPGER) bound to recombinant human α1 and α2 I-domains in a metal ion-dependent manner and without a requirement for hydroxyproline. We predicted a novel and selective integrin-binding sequence, GFPGEN, through the use of computer modeling and demonstrated that Scl2(GFPGEN) shows specificity toward the α1 I-domain and does not bind the α2 I-domain. Using C2C12 cells, we determined that intact integrins interact with the modified Scl2 proteins with the same selectivity as recombinant I-domains. These modified Scl2 proteins also acted as cell attachment substrates for fibroblast, endothelial, and smooth muscle cells. However, the modified Scl2 proteins were unable to aggregate platelets. These results indicate that Scl2 is a suitable backbone for the introduction of mammalian integrin-binding sequences, and these sequences may be manipulated to individually target α1β1 and α2β1.

Summary: Platelet transfusions, main therapy of Glanzmann Thromboasthenia (GT), can induce an allo-immunization against human leucocyte antigen and integrin alphaIIbbeta3. We have investigated in our GT patients the rate of allo-immunization and of refractoriness to platelet transfusions. From 1975 until December 2005, we have followed 17 GT patients: 14 type 1, 3 variant type; nine females, eight males; median age at diagnosis 9.8 years (range 1-44.5); median age at the time of the study 35.5 years (range 23.6-68.5). In our patients, 121 bleeding episodes occurred (24 severe, 37 moderate, and 60 mild). Ten major and 22 minor surgical procedures have been performed. Two spontaneous deliveries and three caesarian sections with five live births were performed; moreover, one late foetal loss occurred, and one voluntary abortion was performed. Sixteen of 17 patients have been transfused at least once in life with platelets and/or red blood cells (RBC). All transfused patients have been investigated for the presence of anti-HLA and anti-integrin alphaIIbbeta3 allo-antibodies. The positiveness of allo-antibodies has been demonstrated in 4/16 transfused patients (25%): isolated for anti-HLA in two; isolated for anti-integrin alphaIIbbeta3 in one; and combined in one. In spite of the presence of allo-antibodies, platelet transfusions have always been effective and the haemostasis was not compromised.

Coronary atherosclerosis is a complex and progressive condition that involves many biological pathways, including the oxidative stress and inflammatory response pathways. To investigate the association between common genetic variation within these two pathways and coronary atherosclerosis, we performed a comprehensive two-stage candidate gene association study in a Chinese Han population. In stage I, 936 tag single-nucleotide polymorphisms (SNPs) within 116 candidate genes were genotyped in 293 coronary atherosclerosis cases and 293 age- and gender-matched healthy controls. In stage II, 51 SNPs from stage I were selected and further genotyped in an additional 1030 cases and 764 controls. In allele- and genotype-based association tests of stage II and a meta-analysis across the two stages, we identified three SNPs within three genes significantly associated with the disease, namely rs3212556 in ITGA2 (P(CMH)=9.20 x 10(-5)), rs854563 in PON1 (P(CMH)=1.92 x 10(-4)) and rs9283851 in THBS2 (P(CMH)=3.00 x 10(-3)). Haplotype analysis provided further supporting evidence for the association of rs3212556 (P(global)<10(-4)) and rs854563 (P(global)<10(-4)). Our study has identified three SNPs within ITGA2, PON1 and THBS2 that are associated with coronary atherosclerosis.

Von Willebrand disease (VWD) is one of the most common inherited bleeding diseases caused by a qualitative or quantitative deficiency of the von Willebrand factor (FvW). FvW is a multimeric glycoprotein synthesized by megakaryocytes and endothelial cells and it is present in the subendothelial matrix, blood plasma, platelets, and endothelium. This glycoprotein plays an important role in thrombus formation by initiating platelet adhesion to sites of injury as well as platelet aggregation. The aim of this study was to evaluate the activities of enzymes that hydrolyze adenine nucleotides in platelets, ristocetin-induced platelet aggregation (RIPA), and polymorphisms of the alpha2 gene of alpha2beta1 integrin from VWD patients. Platelet nucleoside triphosphate diphosphohydrolase (NTPDase), 5'-nucleotidase, and ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP) activities were verified in 14 VWD patients. For RIPA determination, a final concentration of 1.25 mg/ml of ristocetin was used. Polymorphisms of the alpha2 gene were analyzed through PCR. Platelet NTPDase and E-NPP were decreased in VWD patients. 5'-Nucleotidase activity was not statistically significant between controls and VWD patients. RIPA was significantly reduced, with an allelic frequency of 78.57% for 807C in VWD patients. Our results indicated reduced platelet NTPDase and E-NPP activities which might be related to the low platelet adhesiveness. The prevalence of the 807C allele might account for the variability in bleeding in VWD.

Type 2B von Willebrand disease (2B VWD) results from von Willebrand factor (VWF) A1 mutations that enhance VWF-GPIbalpha binding. These "gain of function" mutations lead to an increased affinity of the mutant VWF for platelets and the binding of mutant high-molecular-weight VWF multimers to platelets in vivo, resulting in an increase in clearance of both platelets and VWF. Three common 2B VWD mutations (R1306W, V1316M, and R1341Q) were independently introduced into the mouse Vwf cDNA sequence and the expression vectors delivered to 8- to 10-week-old C57Bl6 VWF(-/-) mice, using hydrodynamic injection. The resultant phenotype was examined, and a ferric chloride-induced injury model was used to examine the thrombogenic effect of the 2B VWD variants in mice. Reconstitution of only the plasma component of VWF resulted in the generation of the 2B VWD phenotype in mice. Variable thrombocytopenia was observed in mice expressing 2B VWF, mimicking the severity seen in 2B VWD patients: mice expressing the V1316M mutation showed the most severe thrombocytopenia. Ferric chloride-induced injury to cremaster arterioles showed a marked reduction in thrombus development and platelet adhesion in the presence of circulating 2B VWF. These defects were only partially rescued by normal platelet transfusions, thus emphasizing the key role of the abnormal plasma VWF environment in 2B VWD.

Objective: Laminin alpha1-chain normally induces intercalated duct progenitors to differentiate to acinar cells through integrin (INT) alpha1ss1 and alpha2ss1 receptors. Maintenance of acinar cells is impaired in Sjögren's syndrome (SS), which is also characterized by low levels of serum and salivary androgens. We hypothesized that androgens normally support salivary gland remodeling by upregulating either laminin alpha1 chain or its cellular alpha1 or alpha2 INT subunit-containing receptors., Methods: Intercalated duct and acinar human salivary gland (HSG) cells and labial salivary gland (LSG) biopsies from healthy controls and patients with SS were cultured without or with sex steroids. Laminin alpha1 chain and INT alpha1 and alpha2 subunits were studied using quantitative reverse-transcription real-time polymerase chain reaction and INT alpha1 and alpha2 subunits using immunofluorescence staining., Results: INT alpha1-subunit and alpha2-subunit messenger RNA (mRNA) levels were increased in intercalated duct and acinar cells by DHEA and testosterone. In contrast, laminin alpha1-chain mRNA levels were not affected. The upregulating effect of DHEA on INT subunits was also seen at the protein level. DHEA also increased mRNA levels of both INT subunits in healthy but not SS LSG., Conclusion: Androgens increased INT alpha1 and alpha2 subunits in tubuloepithelial cells and in healthy LSG, but in SS salivary glands this androgen regulation was defective, which is likely to contribute to defective outside-in signaling, acinar atrophy, and ductal cell hyperplasia.

Background: Glanzmann thrombasthenia (GT) is an autosomal recessive bleeding disorder characterized by the tendency to hemorrhage and the inability of platelets to aggregate in response to agonists. GT is caused by a defect of the platelet glycoprotein IIb/IIIa complex. The objective of this study was to describe the clinical features and the genetic cause of GT in a 6-year-old girl from south China., Methods: A three-generation family was studied. The proband patient aged 6 years and her parents undertook examinations of platelet counts, blood film, bleeding time, platelet aggregation, and flow cytometry. All coding exons of the ITGA2B and ITGB3 genes were amplified by polymerase chain reaction (PCR), and direct sequencing was performed for mutational screening on the patient and normal controls consisted of 52 healthy blood donors. Reverse transcription PCR was conducted to test for exon skipping., Results: The proposita patient showed dispersing platelets, prolonged bleeding time, and severely reduced platelet aggregation in response to the physiological agonists adenosine diphosphate (ADP), epinephrine, collagen, and ristocetin. Flow cytometric measurements showed that the contents of alphaIIb and beta3 were significantly decreased. Sequencing results demonstrated two different types of heterozygous mutations existed in the alphaIIb gene (c.2930delG and IVS15-1delG). The compound mutations were also confirmed in the patient's mother and father separately., Conclusions: The alphaIIbbeta3 deficiency of the proband was caused by two compound ITGA2B mutations, which were first reported in Chinese GT patients. The IVS15-1delG was first confirmed to cause an exon skipping.

Glanzmann thrombasthenia (GT) is an autosomal recessive inherited bleeding disorder characterized by an impaired platelet aggregation due to defects in integrin alphaIIbbeta3 (ITGA2B, ITGB3), a fibrinogen receptor. Mutations from 24 GT patients and two carriers of various origins, Caucasian, North-African and Asian were characterized. Promoter and exon sequences of alphaIIb and beta3 genes were amplified and directly sequenced. Among 29 identified mutations, 17 new allelic variants resulting from nonsense, missense and deletion/insertion mutations were described. RNA alterations were evaluated by using Web servers. The alphaIIb p.S926L, p.V903F, and beta3 p.C38Y, p.M118R, p.G221D substitutions prevented complex expression at the surface of COS-7 cells by altering the alphaIIb or the beta3 subunit structure. As shown by free energy analyses applied on the resolved structure of alphaIIbbeta3 and structural modeling of the mutant, the p.K253M substitution of beta3 helped to define a key role of the K253 in the interaction of the alphaIIb beta-propeller and the beta3 beta-I domains. finally, the alphaIIb p.Q595H substitution allowed cell surface expression of the complex but its corresponding c.2800G>T mutation is predicted to alter normal RNA splicing. In conclusion, our study yielded the discovery of 17 new GT allelic variants, revealed the key role of K253 of alphaIIb for the alphaIIbbeta3 complex formation and provides an additional example of an apparently missense mutation causing a splicing defect., ((c) 2010 Wiley-Liss, Inc.)

To determine the genotype distributions of the polymorphisms in platelet glycoproteins (GP) Ib-alpha, Ia/IIa and IIb/IIIa and their association with clinical arterial thrombosis and preclinical carotid atherosclerosis in type 2 diabetes we studied 229 patients with type 2 diabetes and 229 controls matched by age, gender and ethnicity. Biochemical and haemostasis analyses were performed. The GP Ib-alpha VNTR, GP Ia 807 C/T and GP IIIa Pl(A) polymorphisms were determined by PCR. Thrombotic events were registered and carotid atherosclerosis was evaluated by ultrasound examination. A total of 107 patients had clinical atherothrombosis (CA), 65 subclinical atherosclerosis (SA), and 57 had no evidence of atherosclerosis (NA). There were no differences in allele frequencies and the genotype distribution of platelet GP polymorphisms between diabetic patients and controls. The VNTR Ib-alpha polymorphism was not associated with CA. We found a significant association between CA and the 807T (odds ratio [OR]: 2.86, confidence interval [CI]: 1.65-4.93; p<0.001) and PlA2 (OR: 2.03, CI: 1.13-3.65; p=0.03) alleles (in GP Ia and GP IIIa, respectively) in comparison to SA and NA group. Diabetic patients with the coexistence of the 807T and PlA2 alleles presented the highest risk of CA (OR: 3.59, CI: 1.64-7.8; p<0.001). The coexistence of both 807T and PlA2 alleles was also associated with the presence of SA (OR: 9.00, CI: 1.10-73.42; p=0.04). In conclusion, the 807T allele of GP Ia and the PlA2 allele of GP IIIa, and specially its combination, may confer an additional risk for development of carotid atherosclerosis and arterial thrombosis in type 2 diabetes.

Background: Recent reports suggest that maternal immunization against low-frequency, platelet (PLT)-specific glycoprotein (GP) polymorphisms is a more common cause of neonatal alloimmune thrombocytopenia (NATP) than previously thought., Study Design and Methods: Serologic and molecular studies were performed on PLTs and DNA from three families in which an infant was born with apparent NATP not attributable to maternal immunization against known PLT-specific alloantigens., Results: Antibodies reactive only with paternal PLTs were identified in each mother. In Cases 2 (Kno) and 3 (Nos), but not Case 1 (Sta), antibody recognized paternal GPIIb/IIIa in solid-phase assays. Unique mutations encoding amino acid substitutions in GPIIb (Case 2) or GPIIIa (Cases 1 and 3) were identified in paternal DNA and in DNA from two of the affected infants. Antibody from all three cases recognized recombinant GPIIIa (Case 1 [Sta] and Case 3 [Nos]) and GPIIb (Case 2, Kno) mutated to contain the polymorphisms identified in the respective fathers. None of 100 unselected normal subjects possessed the paternal mutations. Enzyme-linked immunosorbent assay and flow cytometric studies suggested that failure of maternal serum from Case 1 (Sta) to react with paternal GPIIIa in solid-phase assays resulted from use of a monoclonal antibody AP2, for antigen immobilization that competed with the maternal antibody for binding to the Sta epitope., Conclusion: NATP in the three cases was caused by maternal immunization against previously unreported, low-frequency GP polymorphisms. Maternal immunization against low-frequency PLT-specific alloantigens should be considered in cases of apparent NATP not resolved by conventional serologic and molecular testing.

Glanzmann's thrombasthenia (GT) was diagnosed in two patients who presented with bleeding manifestations accompanied by absent platelet aggregation, secondary to adenosine-5'-diphosphate, adrenaline, arachidonic acid and collagen. Flow cytometry analysis for GPIIb/IIIa expression was done using CD61 and CD41 markers in these patients and their family members including siblings. The patients were sub typed as Type I as he had absent glycoproteins (GP) IIb/IIIa. Family studies by flow cytometry showed reduced GPII/IIIa expression in both the parents and one sibling. However, western blot showed abnormal GPIIb protein in all the family members including siblings. It is possible that abnormal GPIIb protein by western blot in family members may reflect their carrier status. Patients' DNA was analyzed for mutation in both the GPIIb and GPIIIa genes by conformational sensitive gel electrophoresis (CSGE), followed by sequencing. CSGE showed defect in exon 12 and the promoter region of GPIIb. By sequence, it was confirmed that both the mutations were homozygous one was c.1028T>C and the other one was M33320.1:g.951G>A. For one of these mutations, restriction fragment length polymorphism (RFLP) was developed to look for the same mutation in all the family members. RFLP was developed using a restriction enzyme (TspRI) against the patient's mutation, c.1028T>C in exon 12 of GPIIb gene. RFLP followed by gel electrophoresis revealed that the mutation was heterozygous in all the family members. The findings by RFLP were double confirmed by direct DNA sequencing of the exon 12 in all the family members. Thus, TspRI marker may be used as a RFLP marker to predict the carriers in GT families, if the patients' mutation status is identified.

Background: We have identified a cytosine-adenosine (CA) repeat length polymorphism in the 5'-regulatory region of the human integrin alpha2 gene ITGA2 that begins at -605. Our objective was to establish the contribution of this polymorphism to the regulation of integrin alpha2beta1 expression, which is known to vary several-fold among normal individuals, and to investigate the underlying mechanism(s)., Methodology/principal Findings: In combination with the SNP C-52T, previously identified by us as a binding site for the transcription factor Sp1, four ITGA2 haplotypes can be distinguished, in the order in which they enhance ITGA2 transcription: (CA)(12)/-52C>(CA)(11)/-52C>(CA)(11)/-52T>(CA)(10)/-52T. By DNA affinity chromatography and chromatin immunoprecipitation (ChIP) assays, we show that poly (ADP-ribose)polymerase-1 (PARP-1) and Ku80/70 bind specifically and with enhanced affinity to the longer (CA)(12) repeat alleles., Conclusions/significance: The increased binding of PARP-1 and Ku80/70, known components of transcription co-activator complexes, to the longer (CA)(12) alleles of ITGA2 coincides with enhanced alpha2beta1 expression. The most likely explanation for these findings is that PARP-1 and Ku80/70 contribute to the transcriptional regulation of ITGA2. These observations provide new insight into the mechanisms(s) underlying haplotype-dependent variability in integrin alpha2beta1 expression in human platelets and other cells.

Sustained blood cell production depends on divisions by hematopoietic stem cells (HSCs) that yield both differentiating progeny as well as new HSCs via self-renewal. Differentiating progeny remain capable of self-renewal, but only HSCs sustain self-renewal through successive divisions securely enough to maintain clones that persist life-long. Until recently, the first identified next stage consisted of "short-term" reconstituting cells able to sustain clones of differentiating cells for only 4-6 weeks. Here we expand evidence for a numerically dominant "intermediate-term" multipotent HSC stage in mice whose clones persist for 6-8 months before becoming extinct and that are separable from both short-term as well as permanently reconstituting "long-term" HSCs. The findings suggest that the first step in stem cell differentiation consists not in loss of initial capacity for serial self-renewal divisions, but rather in loss of mechanisms that stabilize self-renewing behavior throughout successive future stem cell divisions., (Copyright 2010 Elsevier Inc. All rights reserved.)

Culture of human osteoblast-like MG-63 cells within collagen gels results in the generation of intrinsic stress. Release of such collagen gels from attachment results in gel contraction and enhanced MMP-1, MMP-3, and alpha2 integrin mRNA levels. To understand the potential role of microtubules and signaling pathways involved in MG-63 cell-mediated contraction and gene expression, cells were cultured in collagen gels. After 24 h collagen gels were released, then immediately treated with nocodazole or specific protein kinase inhibitors. Contraction was assessed, RNA isolated, and real-time PCR analysis performed. Treatment with high concentrations of a microtubule depolymerization agent, nocodazole, enhanced early contraction and led to elevated mRNA levels for MMP-3, whereas low concentrations inhibited contraction at later time points and did not affect mRNA levels. ROCK inhibitor treatment (Y27632) inhibited collagen gel contraction and led to depressed mRNA levels. The ERK1/2 inhibitor U0126 did not affect contraction, but treatment led to depressed MMP-1, MMP-3, and alpha2 mRNA levels. The p38MAPK inhibitor SB203580 modestly affected contraction, but did not affect mRNA levels. These results suggest the potential role of cytoskeletal integrity and multiple kinase signaling pathways in specific bone-remodeling events.

Background: The Platelet Function Analyzer-100 (PFA-100) is widely used to measure platelet reactivity in whole blood under high shear., Objective: To characterize the genetic component of platelet reactivity among normal individuals, using the PFA-100., Methods: We compared baseline platelet reactivity with sex, age, platelet count, hematocrit, plasma von Willebrand factor antigen (VWF:Ag), and alleles of seven candidate genes: integrin subunits alpha2 (ITGA2) and beta3 (ITGB3), platelet glycoproteins GPIbalpha (GP1BA) and GPVI (GP6), purinogenic receptors (P2RY1 and P2RY12) and cyclooxygenase-1 (COX1)., Results: Based on linear and logistic regression models, we report an inverse correlation between baseline closure time (CT) initiated by collagen plus epinephrine (CEPI) and plasma VWF:Ag level, ITGA2 807T and P2RY1 893C, and an inverse correlation between baseline CT initiated by collagen plus adenosine diphosphate (CADP) and P2RY1 893C or GP1BA -5C., Conclusions: These results indicate that genetic polymorphisms in ITGA2 and P2RY1 combine with plasma VWF:Ag levels to modulate baseline platelet reactivity in response to collagen plus EPI, while genetic differences in P2RY1 and GP1BA significantly effect platelet responses to collagen plus ADP. Our results demonstrate that the PFA-100 can be used to evaluate the effects of genetic predictors of platelet function.

Several cell surface molecules have been implicated in rotavirus cell entry, however, their individual relevance during this process is unknown. In this work, the expression of integrins alpha2, beta2, and alpha v beta 3, the heat shock cognate protein 70, and of ganglioside GM1 in different cell lines of human and simian origin was correlated with the infectivity of four rotavirus strains. We observed that different combinations of receptor expression correlated with the infectivity of rotavirus strains, suggesting that the participation of several receptors is important for rotavirus infection. To characterize the relevance of integrins alpha2 and alpha v beta 3 in more detail, their expression was silenced using RNA interference. About 80% decrease in the cell content of integrins resulted in 15-30% decrease of infectivity of strains RRV and Wa when measured by a focus-forming assay, while there was no decrease of infectivity when measured by flow cytometry in integrin-deficient cells. Altogether these data suggest that integrins alpha2 and alpha v beta 3 do not play a major role in the rotavirus entry process.

Four-transmembrane L6 family member 5 (TM4SF5) and its homolog L6, a tumor antigen, form a four-transmembrane L6 family. TM4SF5 expression causes uncontrolled cell proliferation and angiogenesis. Although other genuine transmembrane 4 superfamily (TM4SF) members co-operate with integrins for cell migration, roles of TM4SF5 in the cellular spreading and migration are unknown. Using hepatocarcinoma cell clones that ectopically express TM4SF5, we found that cross talks via an extracellular interaction between TM4SF5 and integrin alpha2 in collagen type I environment inhibited integrin alpha2 functions such as spreading on and migration toward collagen I, which were recovered by suppression of TM4SF5 or structural disturbance of its second extracellular loop using a peptide or mutagenesis. Altogether, the observations suggest that TM4SF5 in hepatocytes negatively regulates integrin alpha2 function via an interaction between the extracellular loop 2 of TM4SF5 and integrin alpha2 during cell spreading on and migration through collagen I environment.

Background: Glanzmann thrombasthenia (GT) is an autosomal recessive inherited platelet function defect that is characterized by reduction in, or absence of, platelet aggregation in response to multiple physiologic agonists. The defect is caused by mutations in the genes encoding ITGA2B or ITGB3. This results in qualitative or quantitative abnormalities of the platelet receptor, alpha IIb-beta 3., Objectives: The aim of this study was to identify the mutations in GT patients and to correlate these with patient phenotype., Subjects and Methods: A total of 45 unrelated patients with GT were enrolled in the present study to identify the causative molecular defects, and also to correlate their phenotype with their genotype. Platelet aggregation, flow cytometry, Western blotting, and mutation screening by conformation sensitive gel electrophoresis (CSGE) followed by sequencing were performed in all patients. Novel mutations were analyzed for penetrance in individual families., Results: A total of 22 novel mutations were identified in 45 unrelated GT patients. Mutations were identified in 36 of the 45 (80%) patients. Missense mutations were seen in most of the GT patients (59%). The remaining mutations were heterogeneous and were distributed throughout the length of the gene. Analysis of family members showed heterozygous mutations in all families., Conclusions: The severe type I GT was the most common subtype found in this study. Missense mutations were identified as the defects responsible for most GT patients. Carrier detection and genetic counseling in these families is a potentially effective alternative for decreasing the burden of severe type of GT.

Background: Fetal/neonatal alloimmune thrombocytopenia (FNAIT) is caused by maternal alloimmunization against fetal platelet (PLT) antigens, inherited from the father and absent from maternal PLTs., Study Design and Methods: A 29-year-old mother gave birth to a severely thrombocytopenic newborn (16 x 10(9) PLTs/L) leading to PLT transfusion therapy associated with intravenous immunoglobulins. The outcome was uneventful. Maternal serum showed a specific positive reaction with the antigen-capture assay (monoclonal antibody [MoAb]-specific immobilization of PLT antigens) only when it was tested with the paternal PLTs and a panel of MoAbs against glycoprotein (GP)Ia-IIa (alpha(2)beta(1) integrin) suggesting the implication of a new PLT antigen., Results: Nucleotide sequence analysis of GPIa cDNA of the father and newborn showed a nucleotide substitution at position 2235 (2235G > T according to the international nomenclature). This substitution induces a Q716H amino acid change in the GPIa mature protein, located outside the I domain involved in cell adhesion for collagen. In vitro analysis of recombinant Chinese hamster ovary (CHO) cells expressing wild-type or mutant (Q716H) human GPIa allowed us to demonstrate that this single amino acid substitution is responsible and sufficient for inducing Cab(a) antigen expression. Adhesion of CHO cells to collagen was not modified by the Cab polymorphism, nor by the maternal anti-Cab(a) alloantibodies, indicating that the mutation does not affect the function of integrin alpha(2)beta(1). In a Caucasian population study, none of the 104 unrelated blood donors was found to be Cab(a)(+)., Conclusion: We describe here a new PLT alloantigen Cab(a) involved in a severe case of FNAIT. Laboratory investigation for the "common" PLT alloantigens is no longer sufficient to evaluate neonatal alloimmune thrombocytopenia in suspected cases.

Objective: To investigate the possible correlation between integrin alpha1, alpha2, and beta1 expression and excessive collagen synthesis in fibroblasts from 3 unrelated Chinese families with hereditary gingival fibromatosis (HGF)., Design: Gingival fibroblasts from three Chinese HGF patients and three healthy subjects were included. The expression of alpha1, alpha2, and beta1 integrin subunits was examined by immunohistochemistry, quantitative PCR, and flow cytometry. We also investigated the effects of transforming growth factor-beta1 (TGF-beta1) on the expression of these integrin subunits., Results: Our results demonstrate that the expression of alpha2 was significantly higher in HGF fibroblasts compared with control fibroblasts (P < 0.01). No significant differences in the expression of alpha1 and beta1 were detected. Furthermore, TGF-beta1 promoted the expression of alpha1 and alpha2 in fibroblasts from both HGF patients and controls. However, it had a larger effect on the expression of alpha2 in HGF fibroblasts than in control cells. In contrast, alpha1 expression was stimulated more in control fibroblasts., Conclusion: The increased expression of integrin alpha2 and the increased response to TGF-beta1 of HGF fibroblasts may be related to the excessive collagen deposition in HGF patients.

Syndecan-2, a transmembrane heparan sulfate proteoglycan, is known to serve as an adhesion receptor, but details of the regulatory mechanism governing syndecan-2 cell adhesion and migration remain unclear. Here, we examined this regulatory mechanism, showing that overexpression of syndecan-2 enhanced collagen adhesion, cell migration and invasion of normal rat intestinal epithelial cells (RIE1), and increased integrin alpha2 expression levels. Interestingly, RIE1 cells transfected with either syndecan-2 or integrin alpha2 showed similar adhesion and migration patterns, and a function-blocking anti-integrin alpha2 antibody abolished syndecan-2-mediated adhesion and migration. Consistent with these findings, transfection of integrin alpha2 siRNA diminished syndecan-2-induced cell migration in HCT116 human colon cancer cells. Taken together, these results demonstrate a novel cooperation between syndecan-2 and integrin alpha2beta1 in adhesion-mediated cell migration and invasion. This interactive dynamic might be a possible mechanism underlying the tumorigenic activities of colon cancer cells.

Circulating platelets exhibit rapid signaling and adhesive responses to collagen that facilitate hemostasis at sites of vessel injury. Because platelets are anuclear, their collagen receptors must be expressed by megakaryocytes, platelet precursors that arise in the collagen-rich environment of the bone marrow. Whether and how megakaryocytes regulate collagen adhesion during their development in the bone marrow are unknown. We find that surface expression of activated, but not wild-type, alpha2 integrins in hematopoietic cells in vivo results in the generation of platelets that lack surface alpha2 receptors. Culture of hematopoietic progenitor cells ex vivo reveals that surface levels of activated, but not wild-type, alpha2 integrin receptors are rapidly down-regulated during cell growth on collagen but reach wild-type levels when cells are grown in the absence of collagen. Progenitor cells that express activated alpha2 integrins are normally distributed in the bone marrow in vivo and exhibit normal migration across a collagen-coated membrane ex vivo. This migration is accompanied by rapid down-regulation of activated surface integrins. These studies identify ligand-dependent removal of activated alpha2 receptors from the cell surface as a mechanism by which integrin function can be negatively regulated in hematopoietic cells during migration between the adhesive environment of the bone marrow and the nonadhesive environment of the circulating blood.

Background: Haemolytic uraemic syndrome (HUS) is a disorder characterized by thrombotic microangiopathy, which is caused in 'typical forms' by gastrointestinal infections with Escherichia Coli species that produce verotoxins. Several studies have identified negative prognostic factors of the disease, among which prolonged oliguria, neurological involvement and increased leukocytosis have been more consistently reported. We have hypothesized that the genetic background may also predispose to the development of typical forms of HUS and may influence the clinical course of the disease., Methods: Fourteen polymorphisms, known to influence the coagulation pathway or the activity of the renin-angiotensin system, have been selected and studied in 150 Italian children with typical forms of HUS. Two hundred healthy Italian children were used as controls., Results: The risk of developing HUS was strongly associated with the platelet glycoprotein 1balpha 145M allele (OR 3.08; CI: 1.62-5.85) (P < 0.001). A significant association was also found with polymorphisms located in the adipocyte-derived leucine aminopeptidase and factor V genes. A longer duration of dialysis was moderately associated with increased leukocytosis and with the 807T allele of the platelet glycoprotein 1a gene. High white blood cell count was also strongly associated with the risk of long-term sequelae (OR 2.91, CI: 1.21-6.98) (P < 0.02), whereas the 1166C allele of the angiotensin II type 1 receptor had a significant protective effect (OR 0.28, CI: 0.09-0.83) (P < 0.02)., Conclusions: These results highlight the role of glycoprotein 1balpha in the physiopathology of typical forms of HUS and show that the genetic background plays a role in the susceptibility and severity of the disease.

The novel class of protein kinase C (nPKC) isoform eta is expressed in platelets, but not much is known about its activation and function. In this study, we investigated the mechanism of activation and functional implications of nPKCeta using pharmacological and gene knock-out approaches. nPKCeta was phosphorylated (at Thr-512) in a time- and concentration-dependent manner by 2MeSADP. Pretreatment of platelets with MRS-2179, a P2Y1 receptor antagonist, or YM-254890, a G(q) blocker, abolished 2MeSADP-induced phosphorylation of nPKCeta. Similarly, ADP failed to activate nPKCeta in platelets isolated from P2Y1 and G(q) knock-out mice. However, pretreatment of platelets with P2Y12 receptor antagonist, AR-C69331MX did not interfere with ADP-induced nPKCeta phosphorylation. In addition, when platelets were activated with 2MeSADP under stirring conditions, although nPKCeta was phosphorylated within 30 s by ADP receptors, it was also dephosphorylated by activated integrin alpha(IIb)beta3 mediated outside-in signaling. Moreover, in the presence of SC-57101, a alpha(IIb)beta3 receptor antagonist, nPKCeta dephosphorylation was inhibited. Furthermore, in murine platelets lacking PP1cgamma, a catalytic subunit of serine/threonine phosphatase, alpha(IIb)beta3 failed to dephosphorylate nPKCeta. Thus, we conclude that ADP activates nPKCeta via P2Y1 receptor and is subsequently dephosphorylated by PP1gamma phosphatase activated by alpha(IIb)beta3 integrin. In addition, pretreatment of platelets with eta-RACK antagonistic peptides, a specific inhibitor of nPKCeta, inhibited ADP-induced thromboxane generation. However, these peptides had no affect on ADP-induced aggregation when thromboxane generation was blocked. In summary, nPKCeta positively regulates agonist-induced thromboxane generation with no effects on platelet aggregation.

The combined phenotypic expression of CD11c(low)B220(+)CD122(+)DX5(+) has been used to define a novel cell type termed IFN-producing killer dendritic cells (IKDC). IKDC readily produce IFN-gamma and demonstrate spontaneous cytotoxic activity toward tumors, suggesting that a modulation of IKDC number may be beneficial in cancer treatment. We examined various mouse strains and found that IKDC number was highly variable between the different strains. A linkage analysis associated the distal arm of chromosome 7 with variations in IKDC number. The genetic contribution of chromosome 7 to the regulation of IKDC number was confirmed through the use of congenic mice. We further demonstrate that IKDC proportion is regulated by intrinsic hematopoietic factors. We discuss the role of various candidate genes in the regulation of this newly described cell type and its implication in therapy.

Objective: To study the association of integrin alpha-2 (ITGA2) gene C807T, integrin beta-3 (ITGB3) gene T176C polymorphisms with ischemic stroke and the effect of the polymorphisms on plasma lipid and lipoprotein levels., Methods: Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing were used to detect the integrin genotypes in 265 patients with ischemic stroke and 280 healthy controls. The plasma lipid and lipoprotein levels were measured by routine method., Results: Plasma total cholesterol (TC), triacylglycerol (TG) and low density lipoprotein-cholesterol (LDL-C) in the patients with ischemic stroke were significantly higher than those in the controls (P< 0.05). The distributions of the ITGB3 gene T176C polymorphism were not different between the ischemic stroke group and control group, but the ITGA2 gene C807T polymorphism was significantly different. The relative risk suffering from ischemic stroke of the T allele carrier was 1.455 times as that of the C allele carrier (OR=1.455, 95%CI: 1.134-1.866). The level of plasma lipid in the T allele carriers was significantly higher than that in the C allele carriers (P< 0.05)., Conclusion: The ITGA2 gene C807T polymorphism was associated with ischemic stroke, the 807 T allele may be a genetic risk factor for ischemic stroke. The ITGA2 gene C807T polymorphism may affect ischemic stroke through plasma lipid and lipoprotein levels.

Background and Aims: Integrins such as alpha(2)beta(1), alpha(IIb)beta(3), and alpha(v)beta(3) have been suggested as key players for cancer development and progression. Several polymorphisms affecting these molecules, two in integrin alpha(2) (ITGA2 807C>T and 1648G>A) and one in beta(3) (ITGB3 176T>C), influence their levels, structure, and possibly their function. To analyze the role of ITGA2 and ITGB3 polymorphisms for colorectal cancer risk and clinical presentation, we performed a case-control study., Materials and Methods: Four hundred thirty-three colorectal cancer patients and 433 healthy sex- and age-matched control subjects were investigated. ITGA2 and ITGB3 polymorphisms were determined by 5'-nuclease assays., Results/findings: The ITGA2 807C>T polymorphism was associated with reduced colorectal cancer risk. In a codominant model, the odds ratio for each additional 807-T allele for colorectal cancer was 0.77 (95% confidence interval 0.64-0.94; p = 0.011). The ITGA2 1648G> and the ITGB3 176T>C polymorphism were not associated with colorectal cancer. None of the three polymorphisms investigated was associated with tumor size, histological grade, presence of primary lymph node metastases, tumor stage, or age at diagnosis., Interpretation/conclusion: We conclude that the ITGA2 807C>T polymorphism may be associated with reduced colorectal cancer risk.

We studied the effect of prophylactic aspirin (ASA) ingestion on platelet function in 463 patients with stroke, transient ischemic attack (TIA) or acute coronary disease (ACD), using the Platelet Function Analyzer-100 (PFA-100). We correlated ASA responsiveness with haplotypes of seven candidate genes, selected for their documented role in platelet function, namely, the genes for integrins alpha2beta1and alphaIIbbeta3 (ITGA2, ITGA2B, and ITGB3), platelet glycoproteins Ibalpha and VI (GPIBA and GP6), the purinergic receptor P2Y1 (P2RY1), and prostaglandin H synthase 1 (PTGS1 = COX1). Non-responsiveness to ASA was defined as the failure of prior ASA ingestion to prolong the PFA-100 closure time (CT) when blood was perfused through cartridges coated with collagen plus epinephrine (CEPI-CT). ASA non-responsiveness was observed in 114 of 463 patients (24.6 %), but was not associated with haplotypes of any of the seven candidate genes. There was also no association between any haplotypes and the CT when blood was perfused through cartridges coated with collagen plus ADP (CADP-CT). The ASA non-responsive cohort had significantly increased whole blood platelet counts (p = 0.03) and plasma von Willebrand Factor antigen levels (p < 0.001), which likely contributes to resistance to the inhibitory effects of ASA in the PFA-100.

Tissue microenvironment plays a critical role in guiding local stem cell differentiation. Within the intervertebral disc, collagen type II and nucleus pulposus (NP) cells are two major components. This study aimed to investigate how collagen type II and NP cells affect adipose tissue-derived stem cells (ASCs) in a 3D environment. ASCs were cultured in collagen type I or type II hydrogels alone, or co-cultured in transwells with micromass NP cells for 4 and 14 days. ASCs seeded in collagen type II gels acquired dentritic cell shapes, and orchestrated cell density-dependent gel contraction rates. Up-regulation of collagen type X, but not of other chondrogenic markers was observed at day 4, irrespective of the hydrogel type. Strikingly, in co-cultures with NP cells, more pronounced differentiation of ASCs along the cartilaginous lineage was observed (up-regulation of collagen IIA, IIB and aggrecan gene expression, as well as stronger alcian blue staining), when ASCs were embedded in collagen type II in comparison with type I hydrogels. Interestingly, strong cellular condensations/aggregations were observed in ASC-seeded type II, but not type I gels, and this aggregation was markedly delayed when the same gels were co-cultured with NP cells. The NP cell-mediated inhibition of ASC aggregation in collagen type II gels coincided with down-regulation of integrin subunit alpha2 gene expression. We conclude that soluble factors released by NP cells can direct chondrogenic differentiation of ASCs in collagen hydrogels, and that combination with a nucleus-mimicking collagen type II microenvironment enhances differentiation towards a more pronounced cartilage/NP lineage relative to collagen type I hydrogels.

Objective: To observe the regulation of bFGF on mRNA expression of integrin subunits alpha2, alpha5, beta1, in osteoblasts., Methods: Osteoblasts were pre-cultured for 24 h with F12 medium containing bFGF with different concentration and planted on the sand blasting titanium disks. Three days after planting, osteoblasts were harvested. The mRNA expression of integrin subunit alpha2, alpha5, beta1, were examined by immunofluorescent quantitative real-time polymerase chain reaction (RT-PCR)., Results: The mRNA expression of integrin beta1 is most abundant and the mRNA expressions of integrin alpha2, as are relatively lower than integrin beta1. In the study, the mRNA expression levels of integrin alpha2, alpha5 and beta1 were up-regulated after bFGF stimulation. However, the effective concentration range of bFGF to the three subunits was different., Conclusion: bFGF could up-regulate the mRNA expression of integrin subunits in osteoblasts.

To investigate the molecular aspects of osteoblastic interactions with a type I collagen matrix, human osteoblast-like MG-63 cells were cultured in three-dimensional (3D) collagen I gels. MG-63 cells in collagen gels expressed higher osteocalcin mRNA levels than cells in monolayer (2D) on polystyrene surfaces. Gel contraction was assessed via releasing the collagen gels from attachment following 24 h incubation in serum free, TGF-beta1-treated, or 1,25-(OH)(2)D(3)-treated media. 10 ng/ml of TGF-beta1 was optimal for enhancing contraction and led to decreased osteocalcin mRNA levels. In contrast, 50 nM 1,25-(OH)(2)D(3) led to increased osteocalcin mRNA levels, but did not affect contraction. Furthermore, the effect of contraction on gene expression was examined by releasing a subset of gels after 24 h and assessing mRNA levels by RT-PCR. Contracting gels exhibited temporally regulated differential increases in MMP-1, MMP-3, and alpha(2) integrin mRNA levels at specific time points post release. Cytochalasin D treatment immediately following release of gels inhibited contraction in a dose-dependent manner as well as prevented upregulation of MMP-1, MMP-3, and alpha2 integrin mRNA levels in contracting gels. These results suggest that osteoblastic cells generate internal loads that may affect specific gene expression, and these changes can be altered in the presence of biomediators.

In malignancies where no universally expressed dominant Ag exists, the use of tumor cell-based vaccines has been proposed. We have modified a mouse neuroblastoma cell line to express either CD80 (B7.1), CD137L (4-1BBL), or both receptors on the tumor cell surface. Vaccines expressing both induce a strong T cell response that is unique in that among responding CD8 T cells, a T effector memory cell (T(EM)) response arises in which a large number of the T(EM) express the alpha-chain of VLA-2, CD49b. We demonstrate using both in vitro and in vivo assays that the CD49b(+) CD8 T cell population is a far more potent antitumor effector cell population than nonfractionated CD8 or CD49b(-) CD8 T cells and that CD49b on vaccine-induced CD8 T cells mediates invasion of a collagen matrix. In in vivo rechallenge studies, CD49b(+) T cells no longer expanded, indicating that CD49b T(EM) expansion is restricted to the initial response to vaccine. To demonstrate a mechanistic link between the expression of costimulatory molecules on the vaccine and CD49b on responding T cells, we stimulated naive T cells in vitro with artificial APC expressing different combinations of anti-CD3, anti-CD28, and CD137L. Although some mRNA encoding CD49b was induced by combining anti-CD3 with anti-CD28 or CD137L, the highest level was induced when all three signals were present. This indicates that CD49b expression results from additive costimulation and that the level of CD49b message serves as an indicator of the effectiveness of T cell activation by a cell-based vaccine.