GMP-140: a receptor for neutrophils and monocytes on activated platelets and endothelium

Lysosomal degradation targets mutant calreticulin and the thrombopoietin receptor in myeloproliferative neoplasms

ABSTRACT

Somatic mutants of calreticulin (CRT) drive myeloproliferative neoplasms (MPNs) via binding to the thrombopoietin receptor (MPL) and aberrant activation of the JAK/STAT pathway. Compared with healthy donors, platelets from mutant CRT-expressing patients with MPN display low cell surface MPL. Additionally, coexpression of MPL with an MPN-linked CRT mutant (CRTDel52) reduces cell surface MPL, suggesting that CRTDel52 may induce MPL degradation. We show that lysosomal degradation is relevant to the turnover of CRTDel52 and MPL. Furthermore, CRTDel52 increases the lysosomal localization and degradation of MPL. Mammalian target of rapamycin (mTOR) inhibitors reduce cellular CRTDel52 and MPL, secreted CRTDel52 levels, and impair CRTDel52-mediated cell proliferation. mTOR inhibition also reduces colony formation and differentiation of CD34+ cells from patients with MPN but not from healthy donors. Together, these findings indicate that low-surface MPL is a biomarker of mutant CRT-mediated MPN and that induced degradation of CRTDel52 and MPL is an avenue for therapeutic intervention.

The roles of P-selectin in cancer cachexia

P-selectin, a cell adhesion molecule of the selectin family, is expressed on the surface of activated endothelial cells (ECs) and platelets. Binding of P-selectin to P-selectin glycoprotein ligand-1 (PSGL-1) supports the leukocytes capture and rolling on stimulated ECs and increases the aggregation of leukocytes and activated platelets. Cancer cachexia is a systemic inflammation disorder characterized by metabolic disturbances, reduced body weight, loss of appetite, fat depletion, and progressive muscle atrophy. Cachexia status is associated with increased pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), which activates ECs to release P-selectin. Single-nucleotide polymorphisms (SNPs) loci of P-selectin encoding gene SELP are associated with higher level of plasma P-selectin and increase the susceptibility to cachexia in cancer patients. Elevated P-selectin expression has been observed in the hypothalamus, liver, and gastrocnemius muscle in animal models with cancer cachexia. Increased P-selectin may cause excessive inflammatory processes, muscle atrophy, and blood hypercoagulation, thus facilitating the development of cancer cachexia. In this review, physiological functions of P-selectin and its potential roles in cancer cachexia have been summarized. We also discuss the therapeutic potential of P-selectin inhibitors for the treatment of cancer cachexia.

Current Status of ABO-incompatible Liver Transplantation

By 2014, strategies to prevent antibody-mediated rejection (AMR) after ABO-incompatible (ABO-I) living donor liver transplantation (LDLT) were established in Japan and expanded primarily to Asia, where LDLT is now the predominant form of LT owing to the scarcity of brain-dead donors. A desensitization protocol consisting of rituximab (375 mg/m 2 ), plasma pheresis, tacrolimus, and mycophenolate mofetil before LDLT, followed by standard immunosuppression, is currently the best option in terms of safety and efficacy. Rituximab administration is now known not to increase the risk of hepatocellular carcinoma recurrence, and the feasibility of rituximab for LDLT for acute liver failure and the need for desensitization before LDLT in children older than 1 y have been documented. Strategies are needed to distinguish patients at high risk of AMR from those at low risk and to adjust immunosuppression to prevent both AMR and infection. Specific single-nucleotide polymorphisms in genes encoding Fcγ receptors affecting the cytotoxicity of rituximab on B cells could be useful for adjusting immunosuppression levels to decrease infectious complications. Immunological accommodation after ABO-I transplantation could be provided by immune factors in both the grafts and recipients.

Correlations of inhaled NO with the cTnI levels and the plasma clotting factor in rabbits with acute massive pulmonary embolism

PURPOSE

To investigate the correlation of inhaled nitric oxide (NO) on plasma levels of cardiac troponin I (cTnI) and von Willebrand factor (vWF), glycoprotein (GP) IIb/IIIa, granule membrane protein 140 (GMP-140) in rabbits with acute massive pulmonary embolism (PE).

METHODS

Thirty apanese white rabbits were divided into 3 groups, thrombus were injected in model group (n = 10), NO were inhalated for 24 h after massive PE in NO group (n = 10), saline were injected in control group (n = 10). The concentrations of vWF, GP IIb/IIIa, GMP-140 and cTnI were tested at 4, 8, 12, 16, 20, and 24 h, Correlation analyses were conducted between cTnI and vWF, GP IIb/IIIa, and GMP-140 by Pearson's correlation.

RESULTS

The concentration of cTnI and vWF, GP IIb/IIIa, and GMP-140 was increased in the model group, compared to control group. In the inhaled group, the concentrations of cTnI, vWF, GP IIb/IIIa, and GMP-140 were reduced compared to model group. There was a positive correlation between cTnI and vWF, GP IIb/IIIa, and GMP-140.

CONCLUSION

Inhaled nitric oxide can lead to a decrease in levels of cardiac troponin I, von Willebrand factor, glycoprotein, and granule membrane protein 140, after an established myocardial damage, provoked by acute massive pulmonary embolism.

Neutrophils recruited through high endothelial venules of the lymph nodes via PNAd intercept disseminating Staphylococcus aureus

Staphylococcus aureus is a skin- and respiratory tract-colonizing bacterium and is the leading cause of community-acquired skin infections. Dissemination of these bacteria into systemic circulation causes bacteremia, which has a high mortality rate. Therefore, understanding the immunologic barriers that prevent dissemination is critical to developing novel treatments. In this study, we demonstrate that an S. aureus breach across skin leads to some migration of the pathogen to the draining lymph node, but no further. While subcapsular sinus (SCS) macrophage in lymph nodes were important in detaining S. aureus, a rapid complement-dependent neutrophil recruitment (independent of the SCS macrophage) via high endothelial venules (HEVs) resulted in high numbers of neutrophils that intercepted the bacteria in the lymph nodes. Peripheral Node Addressin together with its two ligands, L-selectin and platelet P-selectin, are critical for recruiting neutrophils via the HEVs. Almost no neutrophils entered the lymph nodes via lymphatics. Neutrophils actively phagocytosed S. aureus and helped sterilize the lymph nodes and prevent dissemination to blood and other organs.

Relation between unconjugated bilirubin and RDW, neutrophil to lymphocyte ratio, platelet to lymphocyte ratio in Gilbert's syndrome

Background

Unconjugated bilirubin (UCB) plays a protective role in coronary artery disease. Red cell distribution width (RDW), neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) are inflammatory biomarkers and higher levels are related to atherosclerosis and adverse cardiovascular events.

Aim

We aimed to investigate the relation between UCB levels and RDW, NLR, PLR in people with Gilbert’s syndrome (GS).

Materials and methods

We selected 2166 subjects (1082 with GS and 1084 healthy controls) from a database having 33,695 people. RDW, NLR and PLR were investigated in the subjects with GS and compared with the healthy controls. Linear regression analysis was used to evaluate the relation between variables.

Results

NLR and PLR were higher in the subjects with GS compared to the controls (p < 0.001). RDW was similar in both groups (p = 0.318). UCB was negatively correlated with lymphocyte counts (p = 0.040), and positively correlated with RDW (p < 0.001) and PLR (p = 0.037) in the subjects with GS. There was no significant correlation between UCB and NLR (p = 0.078). RDW (p < 0.001) and lymphocyte counts (p = 0.030) were significantly associated with UCB levels in the regression analysis conducted in the subjects with GS.

Conclusion

There is a negative association between UCB and NLR, PLR due to low amounts of lymphocyte counts, which causes increased risk of CVD. These results suggest that the cardio-protective effect of UCB is due to both anti-oxidative and anti-inflammatory ways indirectly.

Occupational benzene exposure from vehicular sources in India and its effect on hematology, lymphocyte subsets and platelet P-selectin expression

Benzene exposure from vehicular sources and its health impact are relatively unexplored in India. We have investigated in this study hematology and lymphocyte subsets of 25 petrol pump attendants, 25 automobile service station workers and 35 controls matched for age, sex and socioeconomic conditions. The participants were non-smoking males of Kolkata (former Calcutta) in eastern India. Compared with controls, the workers had 3.8- times more trans,trans-muconic acid in urine, suggesting higher level of benzene exposure. The exposed subjects had decreased erythrocyte, hemoglobin, lymphocyte and platelet levels, but increased neutrophil, band cells, RBC aniso-poikilocytosis and target cells. In addition, CD4+, CD8+ and CD19+ cells were decreased by 37, 20 and 47% respectively, but CD 16+ 56+ NK cells were increased by 20%. P-selectin expression on platelet surface of the workers was significantly elevated ( P < 0.05), indicating upregulation of platelet activity. In summary, the study revealed high level of benzene exposure from vehicular sources in India, and the exposed subjects had hematological and immunological alterations. Toxicology and Industrial Health 2007; 23: 167—175.

State-of-the-Art Review: Usefulness of Laboratory Techniques for Evaluating Antithrombotic Efficacy of New Therapeutic Strategies

New drugs and new therapeutic strategies are being introduced for the prevention and the management of cardiovascular and thromboembolic disorders. Extensive clinical studies and large-scale epidemiological investigations are conducted to demonstrate the efficacy of these therapeutic approaches. Laboratory assays are invaluable tools for this exploration. We discuss how the new understanding concerning the regulation of the coagulolytic equilibrium offers novel investigation tools. Parameters reflecting the activities of new drugs targeted to their impact site and presenting few side effects are available. In addition to global clotting methods and chromogenic substrate-based assays, introduction of immunoassays has allowed measurement of most of the molecular markers of hemostatic activation. We recommend use of a panel of markers exploring the endothelial damage, the blood cell involvement, the early coagulant pathways' activation (XIIa and VIIa), the thrombin-formation pathways, the fibrin formation, and the evaluation of the global fibrinolytic capacity. When related to the clinical end points, all these laboratory assays offer useful and reliable monitoring of new drugs. They contribute to the establishment of new therapeutic strategies. Key Words: Hemostasis—Activation—Antithrombotic—Therapy— Laboratory monitoring.

PKCθ-regulated signalling in health and disease

Protein kinase Cθ (PKCθ) is a key enzyme in T-lymphocytes where it plays an important role in signal transduction downstream of the activated T-cell receptor (TCR) and the CD28 co-stimulatory receptor. Antigenic stimulation of T-cells triggers PKCθ translocation to the centre of the immunological synapse (IS) at the contact site between antigen-specific T-cells and antigen-presenting cells (APCs). The IS-residing PKCθ phosphorylates and activates effector molecules that transduce signals into distinct subcellular compartments and activate the transcription factors, nuclear factor κB (NF-κB), nuclear factor of activated T-cells (NFAT) and activating protein 1 (AP-1), which are essential for the induction of T-cell-mediated responses. Besides its major biological role in T-cells, PKCθ is expressed in several additional cell types and is involved in a variety of distinct physiological and pathological phenomena. For example, PKCθ is expressed at high levels in platelets where it regulates signal transduction from distinct surface receptors, and is required for optimal platelet activation and aggregation, as well as haemostasis. In addition, PKCθ is involved in physiological processes regulating insulin resistance and susceptibility to obesity, and is expressed at high levels in gastrointestinal stromal tumours (GISTs), although the functional importance of PKCθ in these processes and cell types is not fully clear. The present article briefly reviews selected topics relevant to the biological roles of PKCθ in health and disease.

Bilirubin, platelet activation and heart disease: a missing link to cardiovascular protection in Gilbert's syndrome?

Gilbert's syndrome (GS) is a relatively common condition, inducing a benign, non-hemolytic, unconjugated hyperbilirubinemia. Gilbert's Syndrome is associated with mutation in the Uridine Glucuronosyl Transferase 1A1 (UGT1A1) gene promoter, reducing UGT1A1 activity, which normally conjugates bilirubin allowing its elimination from the blood. Individuals with GS demonstrate mildly elevated plasma antioxidant capacity caused by elevated levels of unconjugated bilirubin (UCB), reduced thiols and glutathione. Interestingly, the development of, and risk of mortality from, cardiovascular disease is remarkably reduced in GS individuals. An explanation for this protection may be explained by bilirubin's ability to inhibit multiple processes that induce platelet hyper-reactivity and thrombosis, thus far under-appreciated in the literature. Reactive oxygen species are produced continuously via metabolic processes and have the potential to oxidatively modify proteins and lipids within cell membranes, which may encourage the development of thrombosis and CVDs. Oxidative stress induced platelet hyper-reactivity significantly increases the risk of thrombosis, which can potentially lead to tissue infarction. Here, we discuss the possible mechanisms by which increased antioxidant status might influence platelet function and link this to cardiovascular protection in GS. In summary, this is the first article to discuss the possible role of bilirubin as an anti-thrombotic agent, which inhibits platelet activation and potentially, organ infarction, which could contribute to the reduced mortality rate in mildly hyperbilirbinemic individuals.

Targeting P-selectin in acute pancreatitis

IMPORTANCE OF THE FIELD

Acute pancreatitis (AP) is a multifactorial disorder not fully understood yet. In particular, the pathogenetic pathways promoting a severe life-threatening course of AP are the subject of ongoing investigations. P-selectin has been shown to play a central role in the complex pathophysiology in AP as well as various other inflammatory conditions.

AREAS COVERED IN THIS REVIEW

P-selectin function in AP is reviewed with focus on its dual function as a mediator of leukocyte recruitment and cell adhesion, which implies the unique effect of linking both inflammation and coagulation, especially in the progression from mild to severe necrotizing AP. Potential therapeutic aspects are discussed with regard to the clinical situation.

WHAT THE READER WILL GAIN

A better understanding of the pathogenic role of P-selectin in AP and of the rationale for a therapeutic blockade.

TAKE HOME MESSAGE

P-selectin is a glycoprotein that mediates the adhesion of activated platelets and leukocytes to the vessel wall in various inflammatory conditions. Both pathophysiological steps are closely linked and play a key role in the course of severe AP. A treatment approach by inhibition of P-selectin could be of distinct interest as a therapeutic option in severe AP.

Effect of Narrow-Band UVB Phototherapy on Soluble Cell Adhesion Molecules in Patients with Psoriasis Vulgaris

This study investigated the effect of narrow-band ultraviolet B (NB-UVB) phototherapy on serum levels of the soluble cell adhesion molecules sE-selectin, sP-selectin, sL-selectin and soluble intercellular adhesion molecule-1 (sICAM-1) in 58 patients with psoriasis vulgaris. Psoriasis Area and Severity Index (PASI) scores significantly decreased after treatment, confirming the efficacy of NB-UVB phototherapy. Serum levels of sE-selectin also decreased significantly after treatment, and levels of sICAM-1 showed a significant correlation with PASI score and with levels of sE-selectin. The efficacy of NB-UVB phototherapy in improving psoriatic lesions may be a function of decreased serum levels of E-selectin. These findings emphasize the complex roles of soluble cell adhesion molecules in the immunopathogenesis of psoriasis.

Levels of soluble CD40 ligand and P-Selectin in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is linked to an increased risk of cardiovascular disease. We aimed to research whether the levels of soluble P-selectin (sP-selectin) and soluble CD40 ligand (sCD40L), markers of endothelial function, are altered in subjects with NAFLD having no confounding factors for atherosclerosis. sCD40L, sP-selectin, and high-sensitivity C-reactive protein (hsCRP) levels, and homeostasis model assessment of insulin resistance (HOMA-IR) indexes were measured in 50 NAFLD subjects and 30 healthy controls. sCD40L, sP-selectin, and hsCRP levels were not significantly different between two groups (P = 0.48, 0.51, and 0.34, respectively). Body mass index, waist circumference, and insulin levels and HOMA indexes were significantly higher in subjects with NAFLD (all P < 0.001). The present data show that sCD40L and sP-selectin may not contribute to the accelerated atherogenesis associated with this clinically relevant condition.

Molecular interactions in cancer cell metastasis

Metastasis, the process by which cancer cells leave the primary tumour, disseminate and form secondary tumours at anatomically distant sites, is a serious clinical problem as it is disseminated disease, which is often impossible to eradicate successfully, that causes the death of most cancer patients. Metastasis results from a complex molecular cascade comprising many steps, all of which are interconnected through a series of adhesive interactions and invasive processes as well as responses to chemotactic stimuli. In spite of its clinical significance, it remains incompletely understood. This review provides an overview of some of the molecular interactions that are critical to metastasis. It summarises the principle molecular players in the major steps of the metastatic cascade. These are: (1) tumour angiogenesis, (2) disaggregation of tumour cells from the primary tumour mass, mediated by cadherins and catenins, (3) invasion of, and migration through, the basement membrane (BM) and extracellular matrix (ECM) surrounding the tumour epithelium, and subsequent invasion of the BM of the endothelium of local blood vessels. This is mediated through integrins and proteases, including urokinase form of plasminogen activator (uPA), matrix metalloproteinases (MMPs) and cathepsins, (4) intravasation of the tumour cells into the blood vessels prior to hematogeneous dissemination to distant sites, (5) adhesion of the circulating tumour cells to the endothelial cell lining at the capillary bed of the target organ site. This occurs through adhesive interactions between cancer cells and endothelial cells involving selectins, integrins and members of the immunoglobulin superfamily (IgSF), (6) invasion of the tumour cells through the endothelial cell layer and surrounding BM (extravasation) and target organ tissue and (7) the development of secondary tumour foci at the target organ site.

Platelet activation in patients with psoriasis: increased plasma levels of platelet-derived microparticles and soluble P-selectin

BACKGROUND

It has recently been established that platelets have an important role in increasing inflammation, in addition to their main role in hemostasis and thrombosis. An increased incidence of occlusive vascular disease has been reported in patients with psoriasis and the pathomechanism of psoriasis may involve platelet activation.

OBJECTIVE

The goal of the study was to establish a clearer explanation of the association between platelet activation and psoriasis activity by investigating the levels of markers of platelet activation in patients with psoriasis and examining the relationship between the marker levels and a severity score for psoriasis.

METHODS

Plasma levels of platelet-derived microparticles (PDMPs) and soluble P-selectin were measured by enzyme-linked immunosorbent assay as markers of platelet activation in 21 patients with psoriasis and 22 healthy control subjects. The relationships between the platelet activation markers and the Psoriasis Area and Severity Index score were investigated.

RESULTS

Plasma PDMPs and soluble P-selectin levels were markedly higher in patients with psoriasis compared with those in healthy control subjects. There was a significant correlation between the PDMPs levels and the Psoriasis Area and Severity Index score, and the increased plasma PDMPs and soluble P-selectin levels were markedly reduced after clinical improvement occurred.

LIMITATIONS

The number of people evaluated was relatively small.

CONCLUSIONS

Our results show that blood platelets are activated in patients with psoriasis, especially in those with extensive disease, and suggest a close association between platelet activation and psoriasis activity. Plasma PDMPs level may be a useful indicator of the severity of psoriasis.

P-selectin expression in cold preserved kidneys in University of Wisconsin and histidine-tryptophan-ketoglutarate solutions

The differences and efficacy of standard preservation solutions in kidney transplantation, University of Wisconsin (UW) and histidine-tryptophan-ketoglutarate (HTK), remain a topic of debate in recent clinical studies. P-selectins represent glycoproteins expressed on endothelial cells and platelets responsible for the earliest events in ischemia/reperfusion injury in kidney transplantation. This study aimed to compare the levels of P-selectin expression between cold preserved kidney tissues in UW and HTK solutions. Thirty kidneys were procured from male Lewis rats and stored in cold (4°C) solutions for periods of 4, 12, 16, 20, and 24h. Group 1 (n=15) kidneys were stored in UW solutions, and group 2 (n=15) kidneys were submerged in HTK solutions. At the end of each time point, the kidneys underwent preparation and levels of P-selectin expression in the tissues were measured using Immunoblot analyses and adjusted volumetric quantification of Western blot signals. For all periods of cold preservation, P-selectin expression was significantly down-regulated in kidney tissues stored in UW compared with HTK solutions (P<0.001). In summary, UW demonstrated a significant benefit over HTK solution in down-regulating P-selectin expression in cold preserved kidney grafts.

Differential stimulation of monocytic cells results in distinct populations of microparticles

BACKGROUND

Microparticles (MPs), small vesicles shed from stimulated cells, permit cross-talk between cells within a particular environment. Their composition is thought to reflect their cell of origin, and differs according to whether they are produced by stimulation or by apoptosis. Whether MP properties vary according to stimulus is not yet known.

METHODS

We studied the characteristics of MPs produced from monocytic THP-1 cells upon stimulation with lipopolysaccharide or a soluble P-selectin chimera, using proteomics, flow cytometry, western blotting, and electron microscopy.

RESULTS

Utilizing a novel criterion of calcein-AM staining to define MPs, we found that MP populations were similar with respect to size, presence and organization of cytoskeleton, and expression of certain antigens. The MPs shared the same level of procoagulant activity. We found that MPs also have distinct characteristics, depending on stimuli. These include differences in phosphatidylserine expression and expression of proteins from specific subcellular locations such as the mitochondria, and of unique antigens such as leukocyte-associated immunoglobin-like-receptor (LAIR)-1, which was found only upon stimulation with the soluble P-selectin chimera.

CONCLUSION

We found that the properties of MPs depend on the stimulus that produced them. This supports the concept that monocytic MPs differentially modulate thrombosis, inflammation and immune regulation according to stimulus.

The effect of intraportal prostaglandin E1 on adhesion molecule expression, inflammatory modulator function, and histology in canine hepatic ischemia/reperfusion injury

BACKGROUND

Prostaglandin E1 (PGE1) is known to protect the liver from I/R, however, the mechanism of cytoprotection is not well understood. This study investigates the effect of intraportal infusion of PGE1 in a warm liver ischemia/reperfusion (I/R) model on cytokines, adhesion molecules and liver structure.

MATERIALS AND METHODS

Twenty dogs underwent laparotomy under general anesthesia. PGE1 (0.02 microg\kg\min) was perfused through the portal vein in the PGE1 group (n = 10), or a similar volume of Ringer's solution in the control group (n = 10) for 15 min. Liver ischemia was induced by hepatic artery and portal vein occlusion and PGE1 was infused via the portal vein for 60 min. The occlusion was released and PGE1 infusion recommenced for 30 min. Blood and liver biopsies were sampled at baseline, 60 min ischemia, and 30 min reperfusion and assessed for transaminases, cytokines, adhesion molecules, and electron microscopy.

RESULTS

PGE1 infusion significantly reduced transaminases TNF-alpha, sICAM-1, sP-selectin, and sE-selectin on ischemia and reperfusion. PGE1 reduced hepatocytic degeneration, portal and central ICAM-1 expression, central and sinusoidal VCAM-1 expression, portal and central P-selectin expression, and portal and sinusoidal E-selectin expression on reperfusion.

CONCLUSION

Intraportal PGE1 infusion reduced I/R injury and was associated with down-regulation of ICAM-1, VCAM-1, P-selectin, and E-selectin on reperfusion.

The plasma levels of soluble P-selectin in subjects with prediabetes

Prediabetes has been associated with an increased risk of cardiovascular disease and mortality. Soluble P-selectin (sP-selectin) is an index of platelet activation and also a risk factor for future vascular events. sP-selectin levels were investigated in prediabetic subjects who had no confounding factors such as hypertension, obesity or dyslipidaemia. sP-selectin, hsCRP levels and HOMA-IR indexes were measured in 40 prediabetic subjects (n = 24 for IFG and n = 16 for IGT) and age-, sex- and BMI-matched 40 healthy controls. sP-selectin levels in prediabetic subjects were not significantly different compared with those in controls (p = 0.12). Prediabetic group had similar hsCRP (p = 0.29), higher HOMA-IR indexes (p < 0.001) and lower HDL cholesterol levels (p = 0.001) when compared with healthy controls. The power of the study was 0.93 for sP-selectin, 0.7 for hsCRP and 1.0 for HOMA. Our data suggest that sP-selectin may not contribute to the prothrombotic state as well as the accelerated atherogenesis associated with prediabetes.

Ischemia-induced angiogenesis: role of inflammatory response mediated by P-selectin

P-selectin is a 140-kDa glycoprotein expressed on endothelial cells and platelets. P-selectin mediates the tethering and rolling of leukocytes along the endothelium, an early step of leukocyte extravasation. Although inflammation is a requisite process for ischemia-induced angiogenesis, little is known regarding the role of P-selectin in angiogenesis in the setting of tissue ischemia. We examined whether ischemia-induced angiogenesis is altered in P-selectin knockout (P-selectin(-/-)) mice. Angiogenesis was evaluated in a surgically induced hind-limb ischemia model using laser Doppler blood flowmetry (LDBF) and histological capillary density (CD). After left hind-limb ischemia, the ischemic/normal limb LDBF ratio was persistently lower in P-selectin(-/-) mice compared with wild-type (WT) mice. CD was also significantly lower in P-selectin(-/-) mice than in WT mice on Postoperative Day 14. Fewer numbers of total CD45+ inflammatory leukocytes infiltrated into the ischemic tissues in P-selectin(-/-) mice than in WT mice, and immunohistochemical analysis revealed the number of infiltrated leukocytes expressing vascular endothelial growth factor was also decreased in P-selectin(-/-) mice. P-selectin mRNA expression was augmented after hind-limb ischemia in WT mice. In conclusion, P-selectin may play an important role in ischemia-induced angiogenesis by promoting early inflammatory mononuclear cell infiltration. P-selectin would become one possible target molecule for modulating inflammatory angiogenesis.

CD24 and human carcinoma: tumor biological aspects

CD24 is a mucin-like adhesion molecule that has recently raised attention and lent substantial improvements for our understanding of tumor biology. Functionally, CD24 enhances the metastatic potential of malignant-cells, because it has been identified as a ligand of P-selectin, an adhesion receptor on activated endothelial cells and platelets. Moreover, it has been described as a diagnostic molecular marker of malignant tumor and for patient prognosis. This article reviews the experimental and clinical data on CD24 expression and carcinomas from the point of view of tumor biology. Based on the research, CD24 expression will be analyzed as a potentially significant parameter for a wide variety of human cancer diagnoses. Understanding the functions and implications CD24 might aid the clinician in the selection of an appropriate therapy for individual patients: for example, the intravenous administration of C1324-specific antibodies to treat cancers.

P-selectin mediates leukocyte rolling in concanavalin-A-induced hepatitis

Concanavalin-A (Con-A)-induced hepatitis is an experimental model of human autoimmune hepatitis characterized by leukocyte activation and infiltration of the liver. The aim of the present study was to evaluate the role of P-selectin on leukocyte-endothelial interactions within the hepatic microvasculature in response to Con-A.

METHODS

The study was performed in P-selectin-deficient mice and wild-type mice pretreated with anti-P-selectin blocking monoclonal antibody (mAb) or vehicle. After 2 h of Con-A (20 mg/kg i.v.) or PBS administration, leukocyte rolling and adhesion and the index of sinusoidal perfusion were evaluated using the intravital microscopy technique in the liver. Apoptosis was determined by flow cytometry analysis of caspase-3 activity assayed on freshly isolated hepatocytes.

RESULTS

Con-A induced a significant increase in leukocyte rolling, mainly located at the central venule (2.1+/-0.4 vs 0.6+/-0.2 cells/min in wild-type mice treated with vehicle) and less marked, but still significant, in portal venules. This was associated with a significant increase in leukocyte adhesion. In P-selectin-deficient mice treated with Con-A, leukocyte rolling in portal and central venules was markedly reduced. However, leukocyte adhesion was only partially attenuated. A few sinusoids were perfused in wild-type mice treated with Con-A (26%). The percentage of perfused sinusoids was significantly higher in P-selectin-deficient mice (45%; P<0.05 vs wild-type). Similar effects were noted after the simultaneous injection of Con-A and anti-P-selecting mAb in wild-type mice. After Con-A treatment, apoptosis was markedly reduced in isolated hepatocytes of P-selectin-deficent mice (37+/-7% vs 75+/-5% in wild type).

CONCLUSION

The results of this intravital microscopy study clearly demonstrate that P-selectin is involved in the initial leukocyte rolling that leads to the development of Con-A-induced liver injury.

C-type natriuretic peptide inhibits leukocyte recruitment and platelet-leukocyte interactions via suppression of P-selectin expression

The multifaceted process of immune cell recruitment to sites of tissue injury is key to the development of an inflammatory response and involved in the pathogenesis of numerous cardiovascular disorders. We recently identified C-type natriuretic peptide (CNP) as an important endothelium-derived mediator that regulates vascular tone and protects against myocardial ischemia/reperfusion injury. Herein, we investigated whether CNP inhibits leukocyte recruitment and platelet aggregation and thereby exerts a potential antiinflammatory influence on the blood vessel wall. We assessed the effects of CNP on leukocyte-endothelial cell interactions in mouse mesenteric postcapillary venules in vivo in animals with high basal leukocyte activation (endothelial nitric oxide synthase knockout mice, eNOS(-/-)) or under acute inflammatory conditions (induced by interleukin-1beta or histamine). CNP suppressed basal leukocyte rolling in eNOS(-/-) mice in a rapid, reversible, and concentration-dependent manner. These effects of CNP were mimicked by the selective natriuretic peptide receptor-C agonist cANF(4-23). CNP also suppressed leukocyte rolling induced by IL-1beta or histamine, inhibited platelet-leukocyte interactions, and prevented thrombin-induced platelet aggregation of human blood. Furthermore, analysis of human umbilical vein endothelial cells, leukocytes, and platelets revealed that CNP selectively attenuates expression of P-selectin. Thus, CNP is a modulator of acute inflammation in the blood vessel wall characterized by leukocyte and platelet activation. These antiinflammatory effects appear to be mediated, at least in part, via suppression of P-selectin expression. These observations suggest that endothelial CNP might maintain an anti-atherogenic influence on the blood vessel wall and represent a target for therapeutic intervention in inflammatory cardiovascular disorders.

Targeted delivery of bone marrow mononuclear cells by ultrasound destruction of microbubbles induces both angiogenesis and arteriogenesis response

OBJECTIVE

Ultrasound (US)-mediated destruction of contrast microbubbles causes capillary rupturing that stimulates arteriogenesis, whereas intramuscular implantation (im) of bone marrow mononuclear cells (BM-MNCs) induces angiogenesis. We therefore studied whether US-targeted microbubble destruction combined with transplantation of BM-MNCs can enhance blood flow restoration by stimulating both angiogenesis and arteriogenesis.

METHODS AND RESULTS

US-mediated destruction of phospholipid-coated microbubbles was applied onto ischemic hindlimb muscle and subsequently BM-MNCs were transfused. A significant enhancement in blood flow recovery after Bubble+US+BM-MNC infusion (34% increase, P<0.05) was observed compared with Bubble+US (25%). The ratio of capillary/muscle fiber increased by Bubble+US+BM-MNC-i.v (260%, P<0.01) than that in the Bubble+US group (172%), into which BM-MNCs were incorporated (angiogenesis). Smooth muscle alpha-actin-positive arterioles were also increased, and angiography showed augmented collateral vessel formation (arteriogenesis). Platelet-derived proinflammatory factors activated by Bubble+US induces the expression of adhesion molecules (P-selectin and ICAM-1), leading to the attachment of transplanted BM-MNCs on the endothelium. Flow assay confirmed that the platelet-derived factors cause the adhesion of BM-MNCs onto endothelium under laminar flow.

CONCLUSIONS

This study demonstrates that the targeted delivery of BM-MNCs by US destruction of microbubbles enhances regional angiogenesis and arteriogenesis response, in which the release of platelet-derived proinflammatory factors activated by Bubble+US play a key role in the attachment of transplanted BM-MNCs onto the endothelial layer.

Quantitative genetic analysis of cellular adhesion molecules: the Fels Longitudinal Study

Circulating concentrations of inflammatory markers predict cardiovascular disease (CVD) risk and are closely associated with obesity. However, little is known concerning genetic influences on serum levels of inflammatory markers. In this study, we estimated the heritability (h2) of soluble cellular adhesion molecule (sCAM) concentrations and examined the correlational architecture between different sCAMs. The study population included 234 men and 270 women aged 18-76 years, belonging to 121 families participating in the Fels Longitudinal Study. Serum levels of soluble intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), E-selectin (sESEL-1) and P-selectin (sPSEL-1) were assayed using commercially available kits. A variance components-based maximum likelihood method was used to estimate the h2 of the different serum inflammatory markers while simultaneously adjusting for the effects of known CVD risk factors, such as age and smoking. Additionally, we used bivariate extensions of these methods to estimate genetic and random environmental correlations among sCAMs. Levels of sCAMs were significantly heritable: h2=0.24+/-0.10 for sICAM-1, h2=0.22+/-0.10 for sVCAM-1, h2=0.50+/-0.11 for sESEL-1, and h2=0.46+/-0.10 for sPSEL-1. In addition, a significant genetic correlation (rho(G)=0.63) was found between sICAM-1 and sVCAM-1 indicating some degree of shared genetic control. In the Fels Longitudinal Study, the levels of four sCAMs are significantly influenced by genetic effects, and sICAM-1 shares a common genetic background with sVCAM-1.

Blood platelet and monocyte activations and relation to stages of liver cirrhosis

AIM: Blood platelets (plt) and monocytes are the cells that play a crucial role in the pathogenesis of liver damage and liver cirrhosis (LC). In this paper, the analysis of mutual relationship between platelets and monocytes activation in LC was conducted.

METHODS: Immunofluorescent flow cytometry was used to measure the percentage of activated platelet populations (CD62P, CD63), the percentage of plt-monocyte aggregates (pma) (CD41/CD45), and activated monocytes (CD11b, CD14, CD16) in the blood of 20 volunteers and 40 patients with LC. Platelet activation markers: sP-selectin, platelet factor 4 (PF4), beta-thromboglobulin (βTG) and monocyte chemotactic peptide-1 (MCP-1) were measured and compared in different stages of LC.

RESULTS: Platelet activation with the increase in both βTG serum concentration and elevation of plt population (CD62P and CD63 as well as MIF CD62P and CD63) is elevated as LC develops and thrombocytopenia rises. There is a positive correlation between medial intensity of fluorescence (MIF) CD62P and MIF CD63 in LC. We did not show any relationship between monocyte activation and pma level. SP-selectin concentration correlates positively with plt count and pma, and negatively with stage of plt activation and MIF CD62P and MIF CD63. There was no correlation between MCP-1 concentration and plt, monocyte activation as well as pma level in LC. CD16 monocytes and MIF CD16 populations are significantly higher in the end stage of LC. A positive correlation occurs between the value of CD11b monocyte population and MIF CD14 and MIF CD16 on monocytes in LC.

CONCLUSION: Platelet and monocyte activation plays an important role in LC. Platelet activation stage does not influence monocyte activation and production of plt aggregates with monocytes in LC. With LC development, thrombocytopenia may be the result of plt consumption in platelet-monocyte aggregates.

PDE4 inhibitors as new anti-inflammatory drugs: effects on cell trafficking and cell adhesion molecules expression

Phosphodiesterase 4 (PDE4) is a major cyclic AMP-hydrolyzing enzyme in inflammatory and immunomodulatory cells. The wide range of inflammatory mechanisms under control by PDE4 points to this isoenzyme as an attractive target for new anti-inflammatory drugs. Selective inhibitors of PDE4 have demonstrated a broad spectrum of anti-inflammatory activities including the inhibition of cellular trafficking and microvascular leakage, cytokine and chemokine release from inflammatory cells, reactive oxygen species production, and cell adhesion molecule expression in a variety of in vitro and in vivo experimental models. The initially detected side effects, mainly nausea and emesis, appear at least partially overcome by the 'second generation' PDE4 inhibitors, some of which like roflumilast and cilomilast are in the later stages of clinical development for treatment of chronic obstructive pulmonary disease. These new drugs may also offer opportunities for treatment of other inflammatory diseases.

The mechanisms by which infectious agents may contribute to atherosclerosis and its clinical manifestations

Three infectious agents have recently gained considerable interest as potential pathogens in atherosclerosis and in its clinical manifestations: herpes simplex virus, cytomegalovirus, and Chlamydia pneumoniae. Chronic and often asymptomatic infections with these agents occur widely in the general population. These pathogens may affect atherosclerosis either directly or indirectly. Direct effects on vascular wall cells might include cell lysis, transformation, lipid accumulation, proinflammatory changes, and augmentation of procoagulant activity. Indirect systemic effects may involve induction of acute-phase proteins, establishment of a prothrombotic state, hemodynamic stress caused by tachycardia, increased cardiac output, or a regional inflammatory activation in response to systemic endotoxemia and cytokinemia. The effects of microbial infection, usually in combination with other risk factors (for example, smoking, hyperlipidemia, family history), might promote atherogenesis and eventually trigger acute coronary events.

Increased platelet CD63 and P-selectin expression persist in atherosclerotic ischemic stroke

Platelet activation is an important process in the pathogenesis of atherothrombosis. However, the serial changes of platelet activation in atherosclerotic ischemic stroke have not been determined. In this study, we measured serially platelet expression of CD63 and P-selectin and platelet aggregability to ADP and collagen. Measurements were made 24 and 72 h and 7 and 90 days after the ischemic event in 29 patients with atherosclerotic ischemic stroke. Platelet aggregability was significantly decreased after 72 h compared to that at 24 h of stroke onset. However, platelet CD63 and P-selectin expression remained high even 90 days after the events. These findings suggest that platelet hyperactivation in atherosclerotic ischemic stroke may be sustained for a considerable period.

Effect of mental and physical stress on platelet activation markers in depressed patients and healthy subjects: a pilot study

Depression represents an independent risk factor for developing ischemic heart disease, with platelet hyperactivity possibly serving as an important mediator of this association. In this pilot study we analyzed platelet surface activation markers in response to two stimuli, mental stress and physical activity. Using flow cytometry, we quantified the presence of two functional activation-dependent glycoprotein receptors on platelets' surface (P-selectin, GP53). Platelet reactivity was assessed as the difference in markers' fluorescence intensity before and after stimulation. We included 10 depressed psychiatric inpatients and 10 age- and sex-matched healthy subjects in our study. There was a significant rise in platelet activation markers in both groups associated with the stress protocol. When the effect of stressors was analyzed separately, strenuous physical activity was found to lead to a significant rise in platelet activation markers in depressed patients but not in healthy subjects, although values indicated a higher baseline level of activation in healthy subjects. These preliminary results lend partial support to the hypothesis of an exaggerated platelet reactivity after physical activity in depression, thus possibly contributing to an increased cardiovascular risk in this disorder.

Supplemental nitric oxide and its effect on myocardial injury and function in patients undergoing cardiac surgery with extracorporeal circulation

BACKGROUND

Cardiopulmonary bypass induces a systemic inflammatory response that may contribute to clinical morbidity. Gaseous nitric oxide at relatively low concentrations may elicit peripheral anti-inflammatory effects in addition to a reduction of pulmonary resistances. We examined the effects of 20 ppm of inhaled nitric oxide administered for 8 hours during and after cardiopulmonary bypass.

METHODS AND RESULTS

Twenty-nine consecutive patients undergoing aortic valve replacement combined with aortocoronary bypass were randomly allocated to either 20 ppm of inhaled nitric oxide (n = 14) or no additional inhalatory treatment (n = 15). Blood samples for total creatine kinase, creatine kinase MB fraction, and troponin I measurements were collected at 4, 12, 24, and 48 hours postsurgery. In addition, we collected perioperative blood samples for measurements of circulating nitric oxide by-products and brain natriuretic peptide. Soluble P-selectin was analyzed in blood samples withdrawn from the coronary sinus before and after aortic clamping. The area under the curve of creatine kinase MB fraction (P =.03), total creatine kinase (P =.04), and troponin I (P =.04) levels were significantly decreased in the nitric oxide-treated patients. Moreover, in the same group we observed blunted P-selectin and brain natriuretic peptide release (P =.01 and P =.02, respectively). Nitric oxide inhalation consistently enhanced nitric oxide metabolite levels (P =.01).

CONCLUSIONS

Nitric oxide, when administered as a gas at low concentration, is able to blunt the release of markers of myocardial injury and to antagonize the left ventricular subclinical dysfunction during and immediately after cardiopulmonary bypass. The organ protection could be mediated, at least in part, by its anti-inflammatory properties.

Shiga toxin binds to activated platelets

Hemolytic uremic syndrome (HUS) is associated with acute renal failure in children and can be caused by Shiga toxin (Stx)-producing Escherichia coli. Thrombocytopenia and formation of renal thrombi are characteristic of HUS, suggesting that platelet activation is involved in its pathogenesis. However, whether Shiga toxin directly activates platelets is controversial. The present study evaluates if potential platelet sensitization during isolation by different procedures influences platelet interaction with Shiga toxin. Platelets isolated from sodium citrate anticoagulated blood were exposed during washing to EDTA and higher g forces than platelets prepared from acid-citrate-dextrose (ACD) plasma. Platelet binding of Stx was significantly higher in EDTA-washed preparations relative to ACD-derived platelets. Binding of Stx was also increased with ACD-derived platelets when activated with thrombin (1 U mL-1) and exposure of the Gb3 Stx receptor was detected only on platelets subjected to EDTA, higher g forces or thrombin. EDTA-exposed platelets lost their normal discoid shape and were larger. P-selectin (CD62P) exposure was significantly increased in EDTA-washed preparations relative to ACD-derived platelets, suggesting platelet activation. Taken together, these results suggest that direct binding of Stx occurs only on 'activated' platelets rather than on resting platelets. The ability of Stx to interact with previously activated platelets may be an important element in understanding the pathogenesis of HUS.

Cadaveric versus living-donor livers: differences in inflammatory markers after transplantation

BACKGROUND

Prolonged cold storage of organs for transplantation may lead to inflammatory damage upon reperfusion. The aim of this study was to investigate whether organs from living donors experience less damage upon reperfusion than those retrieved from cadaver donors, where cold ischemia times are significantly longer.

METHODS

Biopsies were obtained from cadaveric (n=23) and living-related donor (LRD) (n=10) liver transplants before and 2 hours after reperfusion. Cryosections were stained with antibodies against neutrophils, platelets, activated platelets, and endothelium.

RESULTS

LRD liver allografts showed minimal changes postreperfusion. In contrast, after reperfusion of cadaver allografts, neutrophil infiltration was detected in 22% and increased expression of von Willebrand factor (vWF), CD41, and P-selectin in 48%, 30%, and 13% of allografts, respectively. In cadaver allografts with deposition of activated platelets expressing either P-selectin or vWF, the cold ischemia time was significantly longer (885 +/- 123 min vs. 608 +/- 214 min, P=0.04; 776.8 +/- 171 min vs. 559.3 +/- 216 min, P=0.01, respectively). Increases in neutrophils and platelets after reperfusion were not significantly associated with clinical events posttransplant. However, in cadaver transplants that experienced early acute rejection, the mean cold ischemia time was significantly longer than in allografts with no rejection (732 +/- 174 min vs. 480 +/- 221 min, P=0.006).

CONCLUSIONS

This study demonstrates that in the clinical situation, cold ischemia causes platelet deposition and neutrophil infiltration after reperfusion of cadaveric liver allografts. These early inflammatory events may contribute to make the graft more susceptible to acute rejection.

Characterization of platelet and soluble-porcine P-selectin (CD62P)

P-selectin (CD62P), an adhesion molecule expressed on activated endothelial cells and platelets, mediates the initial attachment of leukocytes to the stimulated endothelium upon inflammation and the interaction between leukocytes and platelets. A soluble form of P-selectin is present in the serum of healthy individuals as a circulating protein and high levels have been described in various pathological situations. The aim of this study was to characterize P-selectin on porcine platelets and investigate the soluble form of this protein, which are uncharacterized in several animal species including pigs. A new monoclonal antibody (mAb) (SwPsel.1.9) against porcine P-selectin was produced using a mouse cell line transfected with pig P-selectin cDNA. This mAb together with a previously described mAb (P-sel.KO.2.5), produced in our laboratory, was used to develop an ELISA to quantify porcine P-selectin. No significant levels of soluble-porcine P-selectin were observed in healthy animals. However, the total amount of P-selectin measured in porcine platelets was similar to that found in humans. Increased levels of this circulating protein were detected in the plasma from pigs after allograft implantation. In vitro, P-selectin expression on platelet membrane was rapidly induced by PMA and thrombin, as assessed by flow cytometry. However, these activators did not stimulate the release of soluble P-selectin. Analysis of the proteolytic cleavage of this protein from COS-transfected cells revealed that PMA treatment failed to cause the shedding of membrane-bound P-selectin. These data suggest that porcine P-selectin is a suitable marker for inflammation and that the mechanism involved in the generation of circulating P-selectin is not proteolytic release.

Hypoxaemia in sickle cell disease: biomarker modulation and relevance to pathophysiology

BACKGROUND

Nocturnal oxyhaemoglobin desaturation might have a role in CNS complications related to sickle cell disease, and rates of painful crises. We attempted to examine the biological relations, and describe the haematological risk factors for oxyhaemoglobin desaturation.

METHODS

The study population included children with sickle cell disease and controls. Cellular activation was assessed by measurement of soluble vascular cell adhesion molecule 1, P-selectin, L-selectin, and leukotriene B4. Erythrocyte-endothelial adhesion and routine haematological variables were assessed. Oxygen saturation (SaO2) was measured by pulse oximetry while children were awake and asleep. Children with a mean sleeping SaO2 of < or =93% were identified as hypoxaemic. Children were divided into four groups: controls (ten children), HbSC (nine, all normoxic), HbSS normoxic (13), and HbSS hypoxaemic (15).

FINDINGS

Among haematological variables, sleeping SaO2 correlated only with packed-cell volume (r=0.7; p<0.0001). Inverse relations were noted between sleeping SaO2 and adhesion (-0.45; p<0.01), and markers of white-cell (-0.51; p<0.01), platelet (-0.61; p<0.001), and endothelial activation (-0.46; p<0.01). In the HbSS group who had sleeping hypoxaemia, waking SaO2 measurements showed continuing hypoxaemia, with similar correlation between SaO2 and cell activation markers.

INTERPRETATION

Our adhesion-related findings suggest a potential mechanism for the increased occurrence of clinical vaso-occlusive crises in individuals with sickle cell disease who have oxyhaemoglobin desaturation. Release of cellular mediators in hypoxaemia, and the relation between anaemia and oxyhaemoglobin desaturation, suggest that risk factors for stroke, including anaemia, might have a role in CNS-vasculopathy through hypoxia-mediated pathways. Further more, hypoxaemia in the older child also occurs during the day; such mild untreated hypoxia could lead to an increased risk of vaso-occlusive episodes.

The role of inflammation in vascular injury and repair

Inflammation plays a critical role in the vascular response to injury. In particular, mechanical injury using techniques such as balloon angioplasty and stenting results in complex inflammatory reactions which influence proliferation of vessel wall constituents such as endothelial cells, smooth muscle cells, and extracellular matrix proteins. Inflammatory cells are recruited to the injured vessel wall initially as a reparative mechanism; however, these same inflammatory processes are also pivotal in the development of restenotic lesions. Leukocytes serve as the primary inflammatory cells but we now know that platelets produce a number of important inflammatory mediators. This review describes the mechanisms that regulate endothelial cell migration, smooth muscle cell activation, and extracellular matrix protein production, all of which are key components in the inflammatory response to vascular injury.

Platelet chemokines and chemokine receptors: linking hemostasis, inflammation, and host defense

Blood platelets play critical roles in hemostasis, providing rapid essential protection against bleeding and catalyzing the important slower formation of stable blood clots via the coagulation cascade. They are also involved in protection from infection by phagocytosis of pathogens and by secreting chemokines that attract leukocytes. Platelet function usually is activated by primary agonists such as adenosine diphosphate (ADP), thrombin, and collagen, whereas secondary agonists like adrenalin do not induce aggregation on their own but become highly effective in the presence of low levels of primary agonists. Current research has revealed that chemokines represent an important additional class of agonists capable of causing significant activation of platelet function. Early work on platelet alpha-granule proteins suggested that platelet factor 4, now known as CXCL4, modulated aggregation and secretion induced by low agonist levels. Subsequent reports revealed the presence in platelets of messenger RNA for several additional chemokines and chemokine receptors. Three chemokines in particular, CXCL12 (SDF-1), CCL17 (TARC), and CCL22 (MDC), recently have been shown to be strong and rapid activators of platelet aggregation and adhesion after their binding to platelet CXCR4 or CCR4, when acting in combination with low levels of primary agonists. CXCL12 can be secreted by endothelial cells and is present in atherosclerotic plaques, whereas CCL17 and CCL22 are secreted by monocytes and macrophages. Platelet activation leads to the release of alpha-granule chemokines, including CCL3 (MIP-1alpha), CCL5 (RANTES), CCL7 (MCP-3), CCL17, CXCL1 (growth-regulated oncogene-alpha), CXCL5 (ENA-78), and CXCL8 (IL-8), which attract leukocytes and further activate other platelets. These findings help to provide a direct linkage between hemostasis, infection, and inflammation and the development of atherosclerosis.

Expression of junctional proteins in human platelets

Platelets play a major role in thrombosis and hemostasis by binding the sub-endothelial matrix at sites of injury, but also participate in vascular pathologies such as atherosclerosis. Recently, junctional proteins like PECAM-I and JAM-family members have been recovered from platelets, therefore we examined what other junctional molecules may be present in platelets. We observed immunoreactivity for APC (147 kD), beta-catenin (92 kD), E-cadherin (120 and 84 kD) and occludin (70-85 kD) by western blotting. Additionally, beta-catenin, pan-reactive cadherins, E-cadherin and occludin were seen to partition with the triton insoluble cytoskeleton in platelets. These proteins were also found in a megakaryocyte (platelet precursor) line, MEG-01. Our data suggest that conventional junctional molecules are expressed in platelets and could possibly participate in aggregation, clot formation and wound healing.

The P-selectin cytoplasmic domain directs the cellular storage of a recombinant chimeric factor IX

Hemophilia B was recognized as a good candidate for gene therapy. Several strategies have been attempted and gave promising results in hemophilic animals but failed to achieve corrective levels in humans. To overcome this inconvenience we aimed to generate intracellular pools of factor (F)IX in cells that are implicated in the hemostatic response, e.g. endothelial cells and platelets. Upon stimulation, these cells release their granule content, which in this case would result in an increase in local FIX concentration, and could locally produce an effective hemostasis. In an attempt to produce an intracellular pool of releasable coagulation FIX, the cytoplasmic domain of the P-selectin (pselCT) molecule was fused to the carboxy-terminal extremity of the human FIX protein. The properties of this chimeric molecule (FIX-pselCT) were studied in AtT20, a cell line which possesses storage granules. As previously shown for transmembrane molecules but not for a soluble protein such as FIX, the pselCT fragment induces the storage of FIX-pselCT. The coagulant activity of FIX-pselCT was not affected by the addition of the pselCT tail. The treatment of AtT20 cells with different inhibitors revealed that FIX-pselCT was not submitted to intracellular degradation and that the half-life of the chimeric molecule was at least two times longer than that of FIX-WT. An immunoelectron microscopic analysis demonstrated a specific localization of FIX-pselCT within the ACTH-containing granules. Cell stimulation using Phorbol Myristrate Acetate (PMA), ionophore A-23187 or 8-Br-cAMP induced efficient release of an active FIX-pselCT. These data demonstrate that the addition of the cytoplasmic domain of P-selectin to FIX modifies the cellular fate of the FIX molecule by directing the recombinant protein toward regulated-secretory granules without altering its coagulant activity.

CD24 is an independent prognostic marker of survival in nonsmall cell lung cancer patients

Originally identified as a B-cell marker, expression of the cell surface molecule CD24 has meanwhile been observed in a variety of human malignancies. It appears to function as a ligand of P-Selectin, an adhesion molecule that is present in activated platelets and endothelial cells. We aimed to determine the rate of CD24 expression in our nonsmall cell lung cancer (NSCLC) collection and to clarify its correlation with clinicopathological parameters including patients' survival. A total of 89 NSCLC were analysed immunohistochemically using a monoclonal CD24 antibody (clone 24C02) and a standard detection system (LSAB, DAKO) on NSCLC tissue microarrays (TMA). The staining was semiquantitatively scored (0, 1+, 2+, 3+) and grouped into high (2+, 3+)- and low (0, 1+)-level expression for statistical analysis. A high level of CD24 expression was observed in 45% of the cases, preferentially adenocarcinomas. Patients whose tumours had a high CD24 expression showed a significantly shorter median survival time of 23 months vs 38 months (P=0.033, log-rank test). Similarly tumour, grading, nodal status and clinical stage were significant prognostic markers in univariate survival analysis. Importantly, in the Cox regression-based multivariate analysis, CD24 expression (P=0.025) together with tumour stage (P=0.006) and grade (P=0.011) proved to be independent prognostic parameters. We hypothesise that the decreased survival of NSCLC patients with strongly CD24-positive tumours is related to an enhanced propensity of haematogenous metastasis formation, which might be P-Selectin mediated.