Platelets as inflammatory cells

Thrombo-Inflammation: A Focus on NTPDase1/CD39

There is increasing evidence for a link between inflammation and thrombosis. Following tissue injury, vascular endothelium becomes activated, losing its antithrombotic properties whereas inflammatory mediators build up a prothrombotic environment. Platelets are the first elements to be activated following endothelial damage; they participate in physiological haemostasis, but also in inflammatory and thrombotic events occurring in an injured tissue. While physiological haemostasis develops rapidly to prevent excessive blood loss in the endothelium activated by inflammation, hypoxia or by altered blood flow, thrombosis develops slowly. Activated platelets release the content of their granules, including ATP and ADP released from their dense granules. Ectonucleoside triphosphate diphosphohydrolase-1 (NTPDase1)/CD39 dephosphorylates ATP to ADP and to AMP, which in turn, is hydrolysed to adenosine by ecto-5'-nucleotidase (CD73). NTPDase1/CD39 has emerged has an important molecule in the vasculature and on platelet surfaces; it limits thrombotic events and contributes to maintain the antithrombotic properties of endothelium. The aim of the present review is to provide an overview of platelets as cellular elements interfacing haemostasis and inflammation, with a particular focus on the emerging role of NTPDase1/CD39 in controlling both processes.

Dysregulation of Key Proteinases in Aspergillus fumigatus Induced by Blood Platelets

Background

Aspergillus fumigatus is the most common species causing invasive aspergillosis (IA), a life-threatening infection with more than 80% mortality. Interactions between A. fumigatus and human blood platelets lead to intravascular thrombosis and localized infarcts. To better understand A. fumigatus pathogenesis, we aimed to analyze the genetic basis of interactions between the pathogen and blood platelets.

Methods

A bioinformatic pipeline on microarray gene expression dataset, including analysis of differentially expressed genes (DEGs) using Limma R package and their molecular function, as well as biological pathways identification, was conducted to find the effective genes involved in IA. In the wet phase, the gene expression patterns following fungal exposure to blood platelets at 15, 30, 60, and 180 min were evaluated by quantitative reverse transcriptase-PCR analysis.

Results

Three genes encoding aspartic endopeptidases including (Pep1), (Asp f 13), and (β-glucanase) were the standing candidates. The invasion-promoting fungal proteinase-encoding genes were down-regulated after 30 min of hyphal incubation with blood platelets, and then up-regulated at 60 and 180 min, although only Pep1 was greater than the control at the 60and 180 min time points. Also, the same genes were downregulated in more the clinical isolates relative to the standard strain CBS 144.89.

Conclusion

Our findings delineate the possible induction of fungal-encoded proteinases by blood platelets. This provides a new research line into A. fumigatus' molecular pathogenesis. Such insight into IA pathogenesis might also guide researchers toward novel platelet-based therapies that involve molecular interventions, especially in IA patients.

The Dual Role of Platelets in the Cardiovascular Risk of Chronic Inflammation

Patients with chronic inflammatory diseases often exhibit cardiovascular risk. This risk is associated with the systemic inflammation that persists in these patients, causing a sustained endothelial activation. Different mechanisms have been considered responsible for this systemic inflammation, among which activated platelets have been regarded as a major player. However, in recent years, the role of platelets has become controversial. Not only can this subcellular component release pro- and anti-inflammatory mediators, but it can also bind to different subsets of circulating lymphocytes, monocytes and neutrophils modulating their function in either direction. How platelets exert this dual role is not yet fully understood.

Anoctamin 1 antagonism potentiates conventional tocolytic-mediated relaxation of pregnant human uterine smooth muscle

BACKGROUND

Currently available tocolytic agents are not effective treatment for preterm labor beyond 48 h. A major reason is the development of maternal side effects which preclude the maintenance of an effective steady-state drug concentration. One strategy that can mitigate these side effects is utilizing synergistic drug combinations to reduce the drug concentrations necessary to elicit a clinical effect. We have previously shown that three anoctamin 1 (ANO1) antagonists mediate potent relaxation of precontracted human uterine smooth muscle (USM). In this study, we aimed to determine whether a combination of sub-relaxatory doses of tocolytic drugs in current clinical use [the L-type voltage-gated calcium channel (VGCC) blocker, nifedipine (NIF); and the β2-adrenergic (β2AR) agonist, terbutaline (TRB)] will potentiate USM relaxation with two ANO1 antagonists [benzbromarone (BB) and MONNA (MN)].

OBJECTIVE

This study sought to examine the synergistic potency and mechanistic basis of two ANO1 antagonists with currently available tocolytic drugs. Functional endpoints assessed included relaxation of pre-contracting pregnant human USM tissue, inhibition of intracellular calcium release, and reduction of spontaneous transient inward current (STIC) recordings in human uterine smooth muscle cells.

METHODS

Human myometrial strips and primary human USM cells were used in organ bath and calcium flux experiments with different combinations of sub-threshold doses of ANO1 antagonists and terbutaline or nifedipine to determine if ANO1 antagonists potentiate tocolytic drugs.

RESULTS

The combination of sub-threshold doses of two ANO1 antagonists and current tocolytic drugs demonstrate a significant degree of synergy to relax human pregnant USM compared to the effects achieved when these drugs are administered individually.

CONCLUSION

A combination of sub-threshold doses of VGCC blocker and β2AR agonist with ANO1 antagonists potentiates relaxation of oxytocin-induced contractility and calcium flux in human USM ex vivo. Our findings may serve as a foundation for novel tocolytic drug combinations.

Changes in inflammatory/cardiac markers of HIV positive patients

HIV replication promotes atherogenesis and participates in the immune response to the virus, thereby influencing the inflammatory profile. These changes may, in turn, contribute to the risk of cardiovascular diseases with involvement of platelets. However, adenine nucleotides and nucleosides involved in thromboregulation and modulation of immune response may therefore be affected by these alterations.

OBJECTIVES

This study sought to evaluate the profile of pro and anti-inflammatory cytokines (IL-10, IL-6, IL-17, TNF, IL-4, IL-2 and IFN-gamma), cardiac markers (troponin, CK, CK MB, LDH, CRP) in HIV-positive patients and assess the in vitro effect of antiretroviral therapy on the activities of ectonucleotidases (E-NTPDase and E-5'-nucleotidase) in human platelets.

DESIGN AND METHODS

Blood samples were obtained from ten HIV positive patients at the Infectious Disease Clinic of the University Hospital of Santa Maria, Brazil and ten HIV negative individuals (control group) for this study.

RESULTS

The results revealed that there were significant (P < 0.05) increases in serum levels of IL-6 and IFN-gamma with no significant (P > 0.05) changes in the serum levels of the cardiac markers investigated (CK, CK-MB, troponin, LDH and CRP). In addition, the ectonucleotidases (E-NTPDase and E-5'-nucleotidase) activities were not altered (P > 0.05) in human platelets when incubated with different antiretroviral drugs in vitro.

CONCLUSIONS

The results of this study suggest that, despite successful treatment, a proinflammatory state is not altered in HIV patients, and that antiretroviral therapy per se does not change the purinergic profile.

The incidence of aspirin resistance in heart transplantation recipients

Introduction

Coronary allograft vasculopathy can cause as many deaths as infections or rejection episodes within 3 years following heart transplantation.

Aim

To compare the aspirin resistance rate in an allograft heart transplantation population and in a control group by laboratory tests including the Aspirin-Resistant Patients Identification Test (ASPItest).

Material and methods

A total of 24 heart recipients (20 men and 4 women) at a mean age of 48 ±13 years who underwent routine clinical follow-up were consecutively enrolled in group 1. The control group consisted of 24 patients (19 men and 5 women) at a mean age of 64 ±7 years waiting for coronary artery bypass grafting in our department. All patients were treated with a standard dose of 75 mg aspirin (ASA) daily.

Results

Aspirin resistance was evaluated by the Multiplate platelet function test. The ASPItest revealed a mean value of 27 ±22 U in the transplant group. Results above 30 U were obtained in 8 (34%) patients, with a mean value of 50.3 ±20.6 U, indicating aspirin resistance. In the control group ASPItest results above 30 U were obtained in 5 (20%) patients, with a mean value of 43.3 ±6.4 U.

Conclusions

There is a high incidence (34% vs. 20%, NS) of ASA resistance in heart transplantation recipients and in the general population, respectively.

CXCL12 regulates platelet activation via the regulator of G-protein signaling 16

The regulators of G protein signaling (RGS) protein superfamily negatively controls G protein-coupled receptor signal transduction pathways. One of the members of this family, RGS16, is highly expressed in megakaryocytes and platelets. Studies of its function in platelet and megakaryocyte biology have been limited, in part, due to lack of pharmacological inhibitors. For example, RGS16 overexpression inhibited CXC chemokine receptor 4 (CXCR4)-mediated megakaryocyte migration. More recent studies showed that the chemokine stromal cell-derived factor (SDF1α or CXCL12) regulates platelet function via CXCR4. Based on these considerations, the present study investigated the capacity of RGS16 to regulate CXCL12-dependent platelet function, using the RGS16 knockout mouse model (Rgs16(-/-)). RGS16-deficient platelets had increased protease activated receptor 4 and collagen-induced aggregation, as well as increased CXCL12-dependent agonist-induced aggregation, dense and alpha granule secretion, integrin αIIbβ3 activation and phosphatidylserine exposure compared to those from WT littermates. CXCL12 alone did not stimulate aggregation or secretion in either RGS16-deficient or WT platelets. Furthermore, platelets from Rgs16(-/-) mice displayed enhanced phosphorylation of ERK and Akt following CXCL12 stimulation relative to controls. Finally, we also found that PKCδ is involved in regulating CXCL12-dependent activation of ERK and Akt, in the Rgs16-deficient platelets. Collectively, our findings provide the first evidence that RGS16 plays an important role in platelet function by modulating CXCL12-dependent platelet activation.

Bacterial and viral induction of chicken thrombocyte inflammatory responses

Thrombocytes express Toll-like receptors (TLRs) that detect bacterial or viral pathogens to signal the release of cytokines and mediators. We examined inflammatory responses when thrombocytes were exposed to four TLR ligands. Treatment of thrombocytes with TLR ligands demonstrates differential effects on gene expression of interleukin (IL)-6. Among the TLR ligands examined, lipopolysaccharide stimulation led to the most significant up-regulation of the IL-6 gene and a significant amount of active IL-6 in thrombocyte culture media. Lipoteichoic acid stimulation led to only marginal up-regulation of IL-6 gene expression. Although gene expression of inducible nitric oxide synthase (iNOS) did not increase due to different ligand exposure, a low level constitutive expression of iNOS was observed in all cases. Only thrombocytes treated with polyinosinic-polycytidylic acid and thymidine homopolymer phosphorothioate oligodeoxynucleotides induced rapid, significant production of nitric oxide. We also observed that thrombocytes are able to respond faster upon TLR ligand exposure compared to MQ.NCSU macrophages.

The effect of a 5-HT2A receptor antagonist on pain-related behavior, endogenous 5-hydroxytryptamine production, and the expression 5-HT2A receptors in dorsal root ganglia in a rat lumbar disc herniation model

STUDY DESIGN

Controlled, interventional, animal study.

OBJECTIVE

To evaluate the effect of a 5-HT2A receptor antagonist on pain-related behavior, endogenous 5-hydroxytryptamine (5-HT) plasma levels, and expression of 5-HT2A receptors in dorsal root ganglia (DRGs) in a rat lumbar disc herniation model.

SUMMARY OF BACKGROUND DATA

Application of nucleus pulposus on the nerve root induces immediate peripheral 5-HT production and the expression of 5-HT2A receptors in the adjacent DRG. However, the efficacy of a 5-HT2A receptor antagonist for pain relief in this situation and the mechanism remain unknown.

METHODS

Autologous nucleus pulposus was applied to the left L5 nerve root of 91 adult female Sprague-Dawley rats. The selective 5-HT2A receptor antagonist sarpogrelate hydrochloride (SPG; 1 mg/kg or 10 mg/kg) or vehicle was administered orally once a day from 1 to 21 days postoperatively. Von Frey tests were used to test pain behavior before and after surgery. To assess the effect of SPG on endogenous 5-HT release surrounding the inflamed nerve root, we measured levels of 5-hydroxyindole acetic acid, a 5-HT metabolite, in plasma. Expression of 5-HT2A receptors in the left L5 DRG was examined with immunoblotting.

RESULTS

The higher dose (10 mg/kg) of SPG significantly improved the mechanical withdrawal thresholds from 5 to 21 days after surgery compared with vehicle treatment. 5-hydroxyindole acetic acid in plasma was not significantly different among any groups at any time points. Both doses of SPG inhibited the expression of 5-HT2A receptors after surgery compared with vehicle treatment.

CONCLUSION

A selective 5-HT2A receptor antagonist attenuated pain-related behavior and suppressed 5-HT2A receptor expression in the DRG, but did not affect peripheral 5-HT production. Selective 5-HT2A receptor antagonists may attenuate sciatica by blocking and downregulating 5-HT2A receptors in DRGs in lumbar disc herniation.

LEVEL OF EVIDENCE

NA.

CD235a (Glycophorin-A) Is the Most Predictive Value Among Different Circulating Cellular Microparticles in Thrombocytopenic Human Immunodeficiency Virus Type 1

BACKGROUND

This study was conducted to assess different cellular microparticles (MPs) in thrombocytopenic human immunodeficiency virus type 1 and their significance as disease activity markers.

METHODS

Thirty-five thrombocytopenic human immunodeficiency diseases and 25 healthy controls with matched age and sex were selected. Viral load was quantitated by COBAS real-time polymerase reaction (PCR) assessment of absolute T-cell subsets CD4, CD8 as a disease progress marker. Platelet MPs, platelet-derived monocyte MPs (CD42a, CD61), erythrocyte MP (CD235a), monocytic MP (CD14), and platelet activity MPs (CD62P, PAC-1) were assessed by multicolor flow cytometry FACSCalibur, while platelet functions were assessed by platelet function analyzer (PFA-100). CD42a, CD61, and platelet activity index represented by PAC-1 and CD62.

RESULTS

P-selectin in HIV-infected patient samples were significantly greater (P < 0.001) than among controls. There was a negative correlation between the proportion of PAC-1 and CD62 P-selectin-positive MPs and levels of CD4(+) T-cell counts (r = -0.403, P = 0.016; r = -0.438, P = 0.008), respectively. There was a negative correlation between collagen-ADP and levels of CD4(+) T-cell counts (r = -0.368, P = 0.03). There was a significant high expression level of CD14 monocyte MPs in patients than controls (P < 0.0001), overexpression of CD235a (P < 0.0001), and no correlation between CD14 and CD4, whereas there was a significant negative correlation with CD235a (r = -0.394, P = 0.019). A linear regression analysis of CD4 as a disease progression marker with other variable indicators in HIV patients showed that CD235a could be the most sensitive predictor similar to CD4.

CONCLUSION

Different cellular MPs and platelets activated in HIV patients could have a role in thrombotic events in these patients.

Differential gene expression in Aspergillus fumigatus induced by human platelets in vitro

Invasive aspergillosis is characterized by vascular invasion and thrombosis. In order to determine the antifungal activity of human platelets, hyphal elongation and metabolic activity of a clinical A. fumigatus isolate were measured. Genome-wide identification of differentially expressed genes in A. fumigatus was performed after exposure to platelets for 15, 30, 60 and 180 min. Data were analyzed by gene ontology annotation as well as functional categories (FunCat) and KEGG enrichment analyses.

Platelets attenuated hyphal elongation and viability of A. fumigatus and in total 584 differentially expressed genes were identified, many of which were associated with regulation of biological processes, stress response, transport and metabolism. FunCat and KEGG enrichment analyses showed stress response and metabolic adaptation to be increased in response to platelets. Our findings demonstrate that A. fumigatus displayed a specific transcriptional response when exposed to platelets, thus reflecting their antifungal activities.

Effects of perioperative immunostimulating nutritional therapy on the phagocytic activity of blood platelets in patients with various clinical stages of gastric cancer

PURPOSE

The aim of this study was to evaluate the total blood platelets count, fraction of phagocytizing thrombocytes (PhT%), and phagocytic index of thrombocytes (PhIT) in gastric cancer considering the stage of the disease, and perioperative immunonutrition support.

METHODS

Our study included 44 patients operated for gastric cancer divided into 2 groups depending on the clinical stage, and 40 healthy volunteers -a control group. Group I included 18 patients with stage I-III locoregional malignancies and Group II included 26 patients with stage IV peritoneal dissemination. All patients received immunonutrition during the perioperative period. The phagocytic activity of blood platelets was assessed by measuring PhT% and PhIT prior to and after nutritional therapy.

RESULTS

In Group I, the pre-treatment PhT% and PhIT amounted to 1.08 and 0.99, respectively, and 1.26, and 1.1 after the therapy (p<0.01). In Group II, pre-treatment PhT% and PhIT were 1.12 and 0.97, after 1.18 and 1.06, respectively (p<0.05). In the controls, PhT% and PhIT were 2.26 and 1.83, respectively, significantly higher comparing to gastric cancer patients (p<0.01).

CONCLUSION

Severe impairment of the thrombocyte phagocytic activity in gastric cancer patients has been found. Phagocytic activity of blood platelets was partially improved as a result of perioperative immunonutrition both in locoregional disease and in peritoneal dissemination.

Effect of prostaglandin E-1 on Wisconsin University and histidine-tryptophan-ketoglutarate preservation solutions on preservation injury of the perfused liver

BACKGROUND

The aim of this study was to investigate the effects of prostaglandin E-1 (PGE-1) on preservation injury in livers perfused with the University of Wisconsin (UW) or histidine-tryptophan-ketoglutarate (HTK) solutions.

MATERIALS AND METHODS

Five groups each including six rats included. Ringer's lactate RL (group 1), HTK (group 2), HTK + PGE-1 (group 3), UW (group 4), or UW PGE-1 (group 5). Liver tissue and preservation fluid samples were obtained from the perfused lives for pathological and biochemical examinations respectively at 0, 6 and 12 hours.

RESULTS

Upon biochemical examination, aspartate aminotrasnferase and alanine aminotransferase values were highest among the group with RL solution and lowest with PGE-1. Liver structure was found to be damaged immediately after RL solution, whereas it was preserved in the other four groups. Fewer cellular changes were reported at the end of 12 hours in the groups administered PGE-1 compared with the other groups.

CONCLUSIONS

PGE-1 when applied before preservation protected liver functions, decreased pathologic injury, and delayed changes that occur under cold ischemic conditions.

Neutrophil and platelet complexes and their relevance to neutrophil recruitment and activation

The manifestation of platelet 'satallitism' around neutrophils in whole blood is a long acknowledged phenomenon [1]. Circulating platelet-neutrophil complexes (PNC) occur in a diverse range of inflammatory disorders and infections that affect numerous organs of the body. Animal models have revealed that the formation of PNC is required for the recruitment of neutrophils to inflamed tissue, since platelets 'prime' neutrophils for efficient adhesion to vascular endothelium via the up-regulation of integrins and enhanced responsiveness to chemokines (Fig. 1). Perhaps surprisingly, the surface contact between platelets and neutrophils additionally enhances other neutrophil functions, such as chemotaxis that is required for migration into tissues, trans-cellular production of eicosanoids, phagocytosis and trapping of pathogens, increased respiratory burst leading to the production of reactive oxygen species (ROS), and modulation of neutrophil apoptosis (Fig. 1). Platelet P-selectin appears to have a particular role in enhancing the majority of these activities, and the influence of platelet P-selectin is not therefore confined to the initial rolling events in the process of neutrophil extravasation.

Seasonal influences on CAPs exposures: differential responses in platelet activation, serum cytokines and xenobiotic gene expression

Increasing evidence suggests a role for a systemic pro-coagulant state in the pathogenesis of cardiac dysfunction subsequent to inhalation of airborne particulate matter (PM). We evaluated platelet activation, systemic cytokines and pulmonary gene expression in mice exposed to concentrated ambient particulate matter (CAPs) in the summer of 2008 (S08) and winter of 2009 (W09) from the San Joaquin Valley of California, a region with severe PM pollution episodes. Additionally, we characterized the PM from both exposures including organic compounds, metals, and polycyclic aromatic hydrocarbons. Mice were exposed to an average of 39.01 μg/m(3) of CAPs in the winter and 21.7 μg/m3 CAPs in the summer, in a size range less than 2.5 μm for 6 h/day for 5 days per week for 2 weeks. Platelets were analyzed by flow cytometry for relative size, shape, CD41, P-selectin and lysosomal associated membrane protein-1 (LAMP-1) expression. Platelets from W09 CAPs-exposed animals had a greater response to thrombin stimulation than platelets from S08 CAPs-exposed animals. Serum cytokines were analyzed by bead based immunologic assays. W09 CAPs-exposed mice had elevations in IL-2, MIP-1α, and TNFα. Laser capture microdissection (LCM) of pulmonary vasculature, parenchyma and airways all showed increases in CYP1a1 gene expression. Pulmonary vasculature showed increased expression of ICAM-1 and Nox-2. Our findings demonstrate that W09 CAPs exposure generated a greater systemic pro-inflammatory and pro-coagulant response to inhalation of environmentally derived fine and ultrafine PM. Changes in platelet responsiveness to agonists, seen in both exposures, strongly suggests a role for platelet activation in the cardiovascular and respiratory effects of particulate air pollution.

Fish Oil Supplementation Inhibits Platelet Aggregation and ATP Release Induced by Platelet-activating Factor and Other Agonists

The anti-inflammatory effects of fish oil may partly be due to the inhibition of platelet activation induced by platelet-activating factor (PAF) and other agonists. To investigate this hypothesis, the diets of 12 healthy volunteers were supplemented with 12 fish oil capsules or 12 olive oil capsules daily for 4 weeks in a double blind crossover study. Aggregation induced by PAF (18 and 12.5 nM) and collagen (20 μg/ml)tended to be reduced after fish oil but the effect was statistically significant only in subjects receiving fish oil in the 6rst 4 weeks of the study (P 0.05, n=6). The effect of fish oil supplementation on platelet ATP release was more marked with significant inhibition of ATP release induced by PAF (1200 and 36 nM, P 0.01, n = 12), collagen (20 μg/ml, P 0.005, n = 12) and ADP (15,10 and 5 μM, P 0.05, n = 12). Olive oil supplementation appeared to inhibit ATP release induced by collagen (45 and 30 μg/ml, P> 0.025, n = 12), while aggregation and ATP release induced by arachidonic acid and adrenaline were unaffected by the supplements. Plasma fibrinogen was significantly reduced after olive oil (P 0.01, n = 12) while prothrombin time was reduced after fish oil (P 0.001, n = 12) and olive oil (P 0.0025). Reduced platelet aggregation and more importantly, inhibition of platelet release induced by PAF and other agonists may contribute to the anti-inflammatory effects of fish oil supplementation in a number of disease states but olive oil may also independently affect platelet function and influence the effect offish oil.

Key components of the mode of action for hemangiosarcoma induction in pregabalin-treated mice: evidence of increased bicarbonate, dysregulated erythropoiesis, macrophage activation, and increased angiogenic growth factors in mice but not in rats

In carcinogenicity studies, pregabalin increased hemangiosarcoma incidence in mice but not in rats. Investigative studies, ranging in length from 24 h to 12 months, were conducted in mice (1000 or 5000 mg/kg) and rats (900 mg/kg) to evaluate a potential mode-of-action scheme for tumor formation. Three areas were evaluated: (1) hematopoiesis (because endothelial and hematopoietic cells arise from the same precursor and hemangiosarcomas are primarily located in mouse hematopoietic tissues), (2) angiogenic growth factors (because increased angiogenic growth factors may stimulate vascular tumors), and (3) pulmonary/blood gas parameters (because hypoxia is a known driver for endothelial cell proliferation). In mice, pregabalin rapidly increased platelet and megakaryocyte counts, activated platelets and bone marrow erythrophages, decreased the myeloid-to-erythroid (M:E) ratio (49%), and produced bone marrow and splenic congestion and extramedullary hematopoiesis (EMH). Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor immunohistochemical staining were also increased in mouse bone marrow and spleen and vascular endothelial growth factor receptor 2 immunolabeling was increased in liver. Serum bicarbonate was increased within 24 h of pregabalin administration, persisted over time, and was accompanied by decreased respiratory rate (up to 34%) and increased partial pressure of carbon dioxide (pCO(2)), resulting in sustained metabolic alkalosis and elevated blood pH in mice. In contrast, in rats, pregabalin decreased overall bone marrow cellularity, including decreased number of megakaryocytes (24%) with no evidence of erythrophages, no change in M:E ratio, no EMH, and no increase in angiogenic growth factors or blood pH. Persistent alterations in serum bicarbonate, respiratory function, and blood gas parameters in mice, without adequate compensatory mechanisms, has the potential to create chronic tissue hypoxia, an accepted driver of endothelial cell proliferation.

Interaction of 5-hydroxytryptamine and tumor necrosis factor-α to pain-related behavior by nucleus pulposus applied on the nerve root in rats

STUDY DESIGN

The effects of exogenous 5-hydroxytryptamine (5-HT), tumor necrosis factor(TNF)-α, 5-HT + TNF in combination, and autologous nucleus pulposus (NP) at dorsal root ganglion (DRG) were examined using rat models.

OBJECTIVE

To examine the interaction of 5-HT with TNF for pain-related behavior in a rat lumbar disc herniation (LDH) model.

SUMMARY OF BACKGROUND DATA

5-HT and TNF have been shown to play roles in sciatica in lumbar disc herniation as chemical factors.

METHODS

Adult female Sprague-Dawley rats were divided into six groups: 5-HT group, TNF group, 5-HT + TNF (combination) group, NP group, control group, and naive group. Von Frey tests were used for pain-related behavior testing. Expressions of activating transcription factor 3 and calcitonin gene-related peptide (CGRP) were evaluated immunohistochemically. Expressions of TNF, TNF receptor 1 (TNFR1), and 5-HT2A receptors in the left L5 DRG were examined using western blotting. Plasma levels of 5-hydroxyindole acetic acid, a metabolite of 5-HT, were measured.

RESULTS

Mechanical withdrawal thresholds were significantly decreased in the 5-HT, TNF, combination, and NP groups compared with controls. Thresholds recovered after 14 days in the 5-HT and TNF groups, and after 28 days in the combination group. Exogenous 5-HT and TNF to the nerve root induced pain-related behavior and lasted for a shorter period compared with combination and NP groups. Activating transcription factor 3- and calcitonin gene-related peptide-immunoreactive DRG neurons were significantly increased only in the early phase in 5-HT, TNF, combination, and NP groups. TNF induced 5-HT2A receptor expressions in the DRG, while 5-HT induced TNF and TNF receptor 1 expressions.

CONCLUSION

The present findings suggest that both 5-HT and TNF induce pain-related behavior and interact with each other to prolong pain-related behavior in a rat LDH model.

Macrophage pro-inflammatory cytokine secretion is enhanced following interaction with autologous platelets

BACKGROUND

Macrophages are the dominant phagocyte at sites of wound healing and inflammation, and the cellular and acellular debris encountered by macrophages can have profound effects on their inflammatory profile. Following interaction with apoptotic cells, macrophages are known to switch to an anti-inflammatory phenotype. Activated platelets, however, are also a major component of inflammatory lesions and have been proposed to be pro-inflammatory mediators. In the present study, we tested the hypothesis that macrophage interaction with activated platelets results in an inflammatory response that differs from the response following phagocytosis of apoptotic cells.

METHODS

Human monocyte-derived macrophages (hMDMs) were co-incubated with autologous activated platelets (AAPs) and the platelet-macrophage interaction was examined by electron microscopy and flow cytometry. The cytokines TNF-α, IL-6, and IL-23 were also measured during LPS-activated hMDM co-incubation with AAPs, which was compared to co-incubation with apoptotic lymphocytes. Cytokine secretion was also compared to platelets pre-treated with the gluococorticoid dexamethasone.

RESULTS

Macrophages trapped and phagocytized AAPs utilizing a mechanism that was significantly inhibited by the scavenger receptor ligand fucoidan. LPS-induced macrophage secretion of TNF-α, IL-6, and IL-23 was inhibited by co-incubation with apoptotic cells, but enhanced by co-incubation with AAPs. The platelet-dependent enhancement of LPS-induced cytokines could be reversed by pre-loading the platelets with the glucocorticoid dexamethasone.

CONCLUSIONS

The interaction of human macrophages with autologous platelets results in scavenger-receptor-mediated platelet uptake and enhancement of LPS-induced cytokines. Therefore, the presence of activated platelets at sites of inflammation may exacerbate pro-inflammatory macrophage activation. The possibility of reversing macrophage activation with dexamethasone-loaded platelets is a promising therapeutic approach to treating unresolved inflammation.

Response of blood platelets to beta-glucan from Saccharomyces cerevisiae

The effects of the beta-D-glucan, a polysaccharide derived from the yeast cell walls of species such as Saccharomyces cerevisiae, on blood platelets activation induced by physiological agonists (thrombin, ADP, collagen) in vitro were studied. The aim of our study was to assess in vitro if beta-glucan, a naturally strong biological response modifier, may modify platelet activation, i.e. platelet aggregation and degranulation (release of proteins and adenine nucleotides) induced by thrombin, ADP and collagen. Cytochrome c reduction method was used to test the ability of beta-glucan to change superoxide anion generation in platelets. Moreover, we determined also its effect on enzymatic arachidonic acid cascade. The obtained results indicate that beta-glucan has the inhibitory effects on platelet aggregation and secretion. beta-glucan distinctly reduced the arachidonic acid pathway and superoxide anion radical generation in platelets stimulated by biological agonists. The results of the present study suggest that beta-glucan from Saccharomyces cerevisiae has antiplatelet and antioxidative activities, and therefore may be beneficial in the prevention of the excessive blood platelet activation-related diseases, such as cardiovascular or inflammatory diseases.

Laboratory tests for patients with ileal pouch-anal anastomosis: clinical utility in predicting, diagnosing, and monitoring pouch disorders

Restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the surgical treatment of choice for patients with medically refractory ulcerative colitis (UC) or UC-associated dysplasia, and for the majority of patients with familial adenomatous polyposis. Pouchitis and other complications of IPAA are common. There are scant data on laboratory markers for the evaluation and diagnosis of pouch disorders. The presence of immunogenotypic markers such as genetic polymorphisms of interleukin-1 (IL-1) receptor antagonist, NOD2/CARD15, Toll-like receptor, and tumor necrosis factor-alpha has been reported to be associated with pouchitis. Immunophenotypic/serologic markers such as perinuclear antineutrophil cytoplasmic antibody and anti-CBir1 have been investigated as possible markers for predicting and diagnosing pouchitis. Fecal markers including lactoferrin and calprotectin seem to be useful in distinguishing inflammatory from noninflammatory pouch disorders. In our practice, we have encountered a large number of pouch patients with Clostridium difficile infection. Laboratory evaluation provides information on the etiology and pathogenesis of pouchitis, and it also helps practicing clinicians with accurate diagnosis, differential diagnosis, disease stratification, and management of ileal pouch disorders.

Do Fish Thrombocytes Play an Immunological Role? Their Cytoenzymatic Profiles and Function During an Accidental Piscine Candidiasis in Aquarium

Fish (F) thrombocytes (THRs) from healthy trouts were studied in terms of cytoenzyme expression. FTHRs were positive to acid periodic of shiff (PAS) and acid phosphatase (ac. phos.) without tartaric acid (-TA) stainings, as well to alkaline phosphatase. However, when compared with autologous macrophages (M psi's), they were negative to naphthol cloroacetate esterase (AS-D), alpha-naphthyl acetate esterase (Anae), peroxidase (perox) and control ac. phos. with tartaric acid (+TA) stainings, thus indicating a lack of typical lysosomial enzymes. This evidence supports the notion that FTHRs are not true digesting cells. Quite interestingly, trouts and human M psi's were positive for PAS, AS-D, Anae, and perox stainings, thus confirming that cellular cytochemistries are maintained across evolution as their phagocytic functions. Additionally, blood films from trouts, accidentally infected with Candida albicans in aquarium, were morphologically analyzed. Actually, FTHRs interact with erythrocytes, potentiating the formation of rosettes around a central Mpsi. Polymorph nuclear cells and lymphocytes are present in these cellular aggregates, thus suggesting that FTHRs may represent a link between innate and adaptive immunity.

Participation of 5-hydroxytryptamine in pain-related behavior induced by nucleus pulposus applied on the nerve root in rats

STUDY DESIGN

The role of 5-hydroxytryptamine (5-HT) in sciatica in lumbar disc herniation (LDH) in rats was investigated.

OBJECTIVE

We evaluated the effects of exogenous 5-HT applied on the nerve root on pain-related behavior, the release of endogenous 5-HT in plasma, and the expression of 5-HT2A receptors in dorsal root ganglion (DRG) in a rat LDH model.

SUMMARY OF BACKGROUND DATA

In previous studies, 5-HT2A receptor antagonists improved sciatica in patients with LDH and attenuated pain-related behavior induced by nucleus pulposus applied to the nerve root in rats.

METHODS

Adult female Sprague-Dawley rats were divided into four experimental groups [control group; low-dose (10 microg) 5-HT-group; high-dose (30 microg) 5-HT-group; and autologous nucleus pulposus (NP) and saline group] and each drug was applied to the L5 nerve root. Von Frey tests were used for pain-behavior testing. To assess levels of endogenous 5-HT released in capillaries surrounding inflamed nerve roots, we measured 5-hydroxyindole acetic acid (5-HIAA), a metabolite of 5-HT. Expression of 5-HT2A receptors in the left L5 DRG was examined by immunohistochemical and immunoblotting analyses in the control and NP groups.

RESULTS

Mechanical withdrawal thresholds of the high-dose 5-HT and the NP groups were significantly decreased after surgery compared with the control group and recovered after 14 days in the high-dose 5-HT group. 5-HIAA in plasma was increased by nucleus pulposus applied on the nerve root for 7 days after surgery. The expression of 5-HT2A receptors was enhanced in a time-dependent manner by nucleus pulposus.

CONCLUSION

Exogenous 5-HT to the nerve root induced pain-related behavior with short-lasting effects compared with the nucleus pulposus application. 5-HIAA content in plasma and expression of 5-HT2A receptors in DRG neurons increased early time points after the nucleus pulposus application. These results suggest that 5-HT plays a role in the early phase of the chemical pathogenesis of sciatica in LDH in rats.

Platelet-leucocyte aggregates form in the mesenteric vasculature in patients with ulcerative colitis

BACKGROUND AND AIMS

Inflammation and thrombosis are closely related processes, which may play a role in the pathogenesis, as well as complications, of inflammatory bowel disease (IBD). Platelet activation and platelet-leucocyte aggregation are increased and platelet aggregation is known to occur in the mesenteric vasculature in IBD. The aims of this study were to test the hypotheses that platelet-leucocyte aggregation, platelet activation and neutrophil activation occur in the mesenteric vessels of patients with ulcerative colitis (UC).

PATIENTS AND METHODS

Platelet-leucocyte aggregates (PLAs), platelet activation (P-selectin expression) and neutrophil activation (L-selectin expression, which decreases on neutrophil activation) were assessed flow cytometrically in mesenteric arterial, and venous blood sampled in eight patients with UC and eight controls with colonic carcinoma undergoing intestinal resections.

RESULTS

In the patients with UC, the number of PLAs in the mesenteric vein exceeded that in the artery, the median rise being 38% (P=0.02). In UC, arterial PLA numbers were 0.17 (0.02-0.32) (median, range) x 10(9)/l versus venous 0.26 (0.09-1.6) x 10(9)/l (P=0.02). The median percentage increase was 45%. Mesenteric PLA formation did not occur in patients with colonic carcinoma [arterial 0.06 (0.03-0.49) x 10(9)/l vs. venous 0.05 (0.02-0.35) x 10(9)/l; P=0.55]. The median percentage change was +45% for UC patients and -5% for controls. No arteriovenous gradient was observed in P-selectin expression, but L-selectin expression (arbitrary units), increased in the mesenteric vasculature of the UC patients [arterial 839 (503-995), venous 879 (477-1035); P=0.03] and fell in those with colonic carcinoma [arterial 900 (660-959), venous 850 (546-957); P=0.04]. The median percentage change was +4% for UC and -7% for controls.

CONCLUSION

The finding of increased numbers of PLAs in the venous mesenteric circulation supports the hypothesis that activated vascular endothelium stimulates PLA formation in UC.

Serotonin activates human monocytes and prevents apoptosis

Monocytes play a critical role in chronic atopic dermatitis (AD) and are the primary leukocytes that interact with activated platelets. Although activated platelets release a variety of mediators, the role of platelets in cutaneous allergic inflammation remains unclear. Serotonin (5-hydroxytryptamine, 5-HT) is one of the prototypic mediators produced by activated platelets. We examined the effect of 5-HT on the function and lifespan of human monocytes. Normal human monocytes treated with 5-HT exhibited upregulated expression of costimulatory molecules, enhanced capacity to produce cytokines following lipopolysaccharide treatment, and to stimulate allogeneic CD4+ T cells. 5-HT also attenuated the apoptosis in normal human monocytes in a dose-dependent manner. The plasma levels of 5-HT were increased in patients with AD compared with controls and correlated with the SCORAD index. 5-HT also inhibited monocyte apoptosis in these patients. 5-HT upregulated Bcl-2 and Mcl-1, and inhibited the activation of caspase-3. The effects of 5-HT on monocyte apoptosis were mediated by the 5-HT1 and/or 5-HT7 receptors. 5-HT and a 5-HT(1/6/7)-receptor agonist induced phosphorylation of extracellular signal-regulated kinase1/2 and activation of nuclear transcription factor-kappaB. These findings support that 5-HT activates monocytes and inhibits apoptosis, allowing them to remain in the tissue and contribute to chronic inflammation.

Dynamics of serum C-reactive protein (CRP) level and cosmophysical activity

BACKGROUND

C-reactive protein (CRP), an acute phase reactant, plays an important part in the investigation of the role of inflammation in pathology. Many cardiovascular events show significant associations with various cosmophysical parameters. The aim of this study was to investigate the relationship between the level of CRP and the levels of solar, geomagnetic (GMA), and cosmic ray activity.

METHODS

The results of 25,399 serum CRP tests carried out over a 3-year period were compared with the monthly and daily levels of solar, geomagnetic, and cosmic ray activity during the same period. The cosmophysical data were obtained from the National Oceanic Atmospheric Administration (NOAA) in the U.S. and from the Russian Academy of Science.

RESULTS

On a monthly basis, CRP levels showed no correlation with GMA (n=36, r=0.258, p=0.13), but there was a significant inverse relationship with neutron activity (r=-0.35, p=0.03). For the daily comparisons, CRP levels were significantly correlated with GMA (n=1057, r=0.97, p=0.02), and there was a significant inverse relationship with neutron activity (r=-0.97, p=0.025). Daily neutron activity was higher on days with CRP levels of 0-1.0 mg/dl (n=289) and above1.0-1.5 mg/dl (n=1213) than on days with higher CRP values (>1.5; n=23,897; p<0.0001).

CONCLUSION

The level of serum CRP, in addition to its association with inflammation, is related to the daily level of GMA and inversely to the level of neutron activity.

Effect of serotonin on the differentiation of human monocytes into dendritic cells

The local cytokine environment and presence of stimulatory signals determine whether monocytes acquire dendritic cell (DC) or macrophage characteristics and functions. Because enhanced platelet activation is reported in patients with many allergic disorders, such as atopic dermatitis, platelet-derived factors may influence monocytic differentiation into DC. In this study we examined the effect of serotonin, a prototypic mediator of allergic inflammation released mainly by activated platelets at the inflammatory site, on the granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4-driven differentiation of monocytes into monocyte-derived DC. Monocytes from healthy adult donors were cultured with GM-CSF and IL-4 in the presence or absence of serotonin, and the phenotypes and function of these cells were analysed. In the presence of serotonin, monocytes differentiated into DC with reduced expression of co-stimulatory molecules and CD1a, whereas expression of CD14 was increased. These serotonin-treated DC exhibited significantly reduced stimulatory activity toward allogeneic T cells. However, these cells showed enhanced cytokine-producing capacity, including IL-10 but not IL-12. There was no significant difference between both types of DC in phagocytic activity. Experiments using agonists and antagonists indicated that serotonin 5-hydroxytryptamine (5-HT) induced the alteration of their phenotype and reduction in antigen-presenting capacity were mediated via 5-HTR(1/7). It is therefore suggested that serotonin-driven DC may have a regulatory function in the inflammatory process.

RANTES production from mononuclear cells in response to the specific allergen in asthma patients

BACKGROUND

Eosinophils are considered to be the major inflammatory cells in asthma. Since regulated on activation, normal T expressed and secreted (RANTES) is a potent chemoattractant for various important inflammatory cells such as eosinophils as well as memory T cells potentially recruiting these cells to an inflamed focus, RANTES has been considered to play a key role in various allergic disorders such as asthma.

METHODS

To extend our understanding of the participation of eosinophils and T cells in relation to the production of RANTES in response to the specific allergen in asthma, we examined the production of RANTES from peripheral blood mononuclear cells cultured with specific allergen in atopic asthma patients by a sandwich enzyme-linked immunosorbent assay.

RESULTS

It was revealed that mononuclear cells produced RANTES but not eotaxin in response to the specific allergen in asthma. RANTES production from mononuclear cells of asthma patients with eosinophilia was greater than that of asthma patients without eosinophilia. Moreover, in this study, no differences in RANTES production between CD4 negative cells and CD8 negative cells were observed.

CONCLUSIONS

Taken together, these findings may suggest that mononuclear cells play a crucial role in the pathogenesis, particular in eosinophil and T lymphocyte recruitment into the inflamed focus of asthma through RANTES production in response to the specific allergen.

Close association between activated platelets and neutrophils in the active phase of ulcerative colitis in humans

BACKGROUND

Neutrophils are considered to play a causative role in inflammatory mucosal injury in ulcerative colitis (UC), and an association between platelets and neutrophils may contribute to the progression of the inflammatory processes. To test this hypothesis, we performed immunohistochemical and flow cytometric analyses on tissue and blood samples from patients with UC.

MATERIALS AND METHODS

Colonic mucosal tissues of patients with active (n = 27) or inactive (n = 16) UC and normal controls (n = 11) were subjected to immunohistochemical staining for markers of activated platelets (glycoprotein IIb/IIIa and P-selectin) and neutrophils (neutrophil elastase, myeloperoxidase, and CD66b). The amounts of stained cells were evaluated by computer-aided morphometry. Peripheral blood samples from patients (n = 8) and healthy volunteers (n = 8) were subjected to comparative flow cytometric analysis of activated platelets.

RESULTS

P-selectin-positive activated platelets were frequently aggregated in the inflamed mucosa, especially in ulcerative lesions, and were close to regions of dense neutrophil infiltration. An increase in the number of activated platelets in the colonic lesions was associated with an increase in infiltrating neutrophils and was related to the severity of the disease. The flow cytometric analysis indicated that circulating platelets of patients with UC were highly activated.

CONCLUSIONS

The present study demonstrated that a close association between activated platelets and neutrophils is a prominent pathological change in both the affected colonic mucosa and peripheral blood of patients with active-phase UC. This suggests that platelet-neutrophil association may play an important role in the progression of inflammatory processes in UC.

Peripheral 5-HT2A receptor antagonism attenuates primary thermal hyperalgesia and secondary mechanical allodynia after thermal injury in rats

Inflammation or injury of peripheral tissue causes release of chemical mediators, including 5-hydroxytryptamine (5-HT), which is involved in the facilitation of nociceptive transmission and the induction of hyperalgesia. The present study examined the effect of a selective 5-HT2A receptor antagonist, sarpogrelate, on hyperalgesia and allodynia induced by thermal injury in rats. Mild thermal injury to the hindpaw produces thermal hyperalgesia in the injured area (primary thermal hyperalgesia) and mechanical allodynia in sites adjacent to the primary area (secondary mechanical allodynia). Mechanical allodynia was assessed by paw withdrawal thresholds using von Frey filaments, and thermal hyperalgesia was assessed by paw withdrawal latencies upon exposure to a radiant heat source. Intraperitoneal administration (30-100 mg/kg) or local injection (30-300 microg) of sarpogrelate 10 min prior to thermal injury attenuated secondary mechanical allodynia in a dose-dependent manner. Intraperitoneal administration (3-100 mg/kg) or local injection (30-300 microg) of sarpogrelate 10 min prior to thermal injury attenuated primary thermal hyperalgesia in a dose-dependent manner. Intraplantar injection of sarpogrelate (300 microg) to the contralateral hindpaw had no effect on primary thermal hyperalgesia or secondary mechanical allodynia in the ipsilateral paw. The tissue concentration of 5-HT was measured using microdialysis. Concentrations of 5-HT increased after thermal injury in both primary and secondary areas, and the increase was not attenuated by pretreatment with sarpogrelate (100 mg/kg, i.p.). These data suggest that 5-HT released in peripheral tissues after thermal injury sensitizes primary afferent neurons and produces mechanical allodynia and thermal hyperalgesia via peripheral 5-HT2A receptors.

Elevated Platelet Count before Ileal Pouch–Anal Anastomosis for Ulcerative Colitis is Associated with the Development of Chronic Pouchitis

Acute pouchitis (AP) after ileal pouch–anal anastomosis (IPAA) is common and easily treated. However, chronic pouchitis (CP) remains a difficult management problem and may represent a form of Crohn disease (CD) of the ileal pouch. Because CD patients have higher platelet counts than ulcerative colotis (UC) patients, we prospectively evaluated the association between preoperative platelet count and pouchitis development in 159 patients undergoing IPAA. Reactive thrombocytosis (RT) was defined as a platelet count >450 x 109/L. Median preoperative platelet count was 312 x 109/L (range, 103 x 109/L to 886 x 109/L). One hundred twenty-five patients (79%) had a normal (150 x 109/L to 450 x 109/L) platelet count (-RT patient group). Twenty-eight patients (18%) had RT. Six patients (3%) had a platelet count below 150 x 109/L. After a median follow-up of 13 months, 45 patients (28%) developed pouchitis. Pouchitis developed in 33 +RT patients (26%) versus 9 -RT patients (32%) ( P = NS). UC patients who had +RT had a 25 per cent incidence of CP compared to only 7 per cent of those UC patients who had -RT ( P = 0.03). The incidence of CP was significantly higher after IPAA in UC patients having thrombocytosis before surgery compared to UC patients having a normal platelet count before surgery.

Thrombosis and inflammatory bowel disease

Interaction between thrombosis and inflammation is increasingly recognized. With this, interest has arisen in the role of thrombosis in inflammatory conditions, including the inflammatory bowel diseases. Although the association between active inflammatory bowel disease and thromboembolic complications has long been known, there has been a resurgence in research into the role of thrombosis and the hemostatic system in the pathogenesis of both ulcerative colitis and Crohn's disease. Here we review the increased frequency of thromboembolic complications occurring in patients with inflammatory bowel disease; whether thrombosis might play a part in the initiation and maintenance of inflammation in inflammatory bowel disease; abnormalities of the coagulation system found in patients with inflammatory bowel disease; platelet dysfunction in inflammatory bowel disease; the mechanisms by which hemostatic processes might be proinflammatory in inflammatory bowel disease; and how these interactions might impact not only on the prevention of complications, but also on the treatment of the underlying inflammation in inflammatory bowel disease.

Effects of a 5-HT2A receptor antagonist, sarpogrelate on thermal or inflammatory pain

The effects of intrathecally and systemically administered 5-hydroxytriptamine (5-HT)(2A) receptor antagonist, sarpogrelate on acute thermal or formalin induced pain were examined. Male Sprague-Dawley rats with lumbar intrathecal catheters were tested with their tail withdrawal response to thermal stimulation (tail flick test) or their paw flinching and shaking response by subcutaneous formalin injection into the hind paw (formalin test) after intrathecal or intraperitoneal administration of sarpogrelate. 5-HT(2A) receptor agonist was used to antagonize the effects of sarpogrelate. In the tail flick test, only intraperitoneal administration induced analgesia. In the formalin test, both intrathecal and intraperitoneal administration were analgesic. The analgesic effects were inhibited by pretreatment with 5-HT(2A) receptor agonist. Motor disturbance and behavioral side effects were not observed. In conclusion, sarpogrelate might be analgesic on inflammatory induced acute and facilitated pain by intrathecal or systemic administration. However, only systemic administration could be effective on thermal induced acute pain.

The role of peripheral 5HT2A and 5HT1A receptors on the orofacial formalin test in rats with persistent temporomandibular joint inflammation

The role of peripheral serotonin (5HT) 2A and 5HT1A receptors on the orofacial nocifensive behavioral activities evoked by the injection of formalin into the masseter muscle was evaluated in the rats with persistent temporomandibular joint (TMJ) inflammation evoked by Complete Freund's Adjuvant (CFA). The orofacial nocifensive behavioral activities evoked by the injection of formalin into masseter muscle were significantly enhanced at 1 day (CFA day 1 group) or 7 days (CFA day 7 group) during TMJ inflammation. Pretreatment with local administration of 5HT2A receptor antagonist, ketanserin (0.01, 0.1 mg/rat) into the masseter muscle or systemic administration of ketanserin via i.p. injection (1 mg/kg) reduced the orofacial nocifensive behavioral activities of the late phase evoked by formalin injection into masseter muscle on the side of TMJ inflammation (CFA day 7 group). However, local (0.001-0.1 mg/rat) or systemic (1 mg/kg) administration of 5HT1A receptor antagonist, propranolol, into masseter muscle did not produce the antinociceptive effect in CFA day 7 group. Moreover, local administration of ketanserin (0.1 mg) or propranolol (0.1 mg) into masseter muscle did not inhibit nocifensive orofacial behavior in rats without TMJ inflammation. These data suggest that persistent TMJ inflammation causes the elevation of the orofacial nocifensive behavior, and peripheral 5HT2A receptors play an important role in mediating the deep craniofacial tissue nociception in rats with TMJ inflammation.

Formation of platelet-leukocyte aggregates in inflammatory bowel disease

OBJECTIVES

Formation of platelet-leukocyte aggregates (PLAs) is increased in several inflammatory and thrombotic conditions. This may result from and enhance platelet and neutrophil activation and could contribute to the inflammatory process in inflammatory bowel disease (IBD). We investigated platelet-leukocyte aggregation in patients with IBD and its relation to treatment, disease activity and platelet and neutrophil activation.

METHODS

PLAs, platelet activation (P-selectin expression) and neutrophil activation (L-selectin expression) were assessed 30 and 180 minutes after drawing blood into EDTA/citrate-theophylline-adenosine and dipyridamole, a novel anticoagulant, using fluorescent antibodies to CD45 (for leukocytes), CD42a (for platelets), CD62P (P-selectin) and CD62L (L-selectin) and flow cytometry. Platelet activation was also measured using the ADVIA 120 hematology analyser.

RESULTS

Samples from 67 patients with IBD measured within 30 minutes had a higher platelet count (P < 0.001), more platelets expressing P-selectin (P = 0.01), and more PLAs (P < 0.01) than from 20 healthy controls and more PLAs (P < 0.05) than from 9 controls with inflammatory arthropathies. IBD patients on thiopurines had fewer PLAs than those not taking them (P < 0.05); corticosteroids and aminosalicylates had no such effects. Incubation for 180 minutes increased the number of platelets expressing P-selectin (P < 0.0001), and the number of PLAs (P < 0.0001). The PLAs correlated with the number of platelets expressing P-selectin before (r=+0.40, P < 0.001) and after (r=+0.66, P < 0.0001) incubation.

CONCLUSIONS

The number of PLAs is higher in patients with IBD than in healthy and inflammatory controls, but their numbers are lowered by thiopurines. Increased PLA formation may in part be due to increased platelet activation and could be pathogenic in IBD.

Platelets in inflammatory bowel disease: clinical, pathogenic, and therapeutic implications

Both Crohn's disease (CD) and ulcerative colitis (UC) are associated with abnormalities of platelet number and function. In the peripheral circulation the state of platelet activation is typically increased, and inflammatory bowel disease (IBD)-involved mucosa frequently contains platelet aggregates within mucosal microthrombi. The relevance of platelet dysfunction to IBD pathogenesis is still unclear, but there is solid evidence demonstrating that platelets, in addition to their traditional role in hemostasis, can also function as potent proinflammatory cells. Upon activation, platelets secrete a large number of biologically active molecules able to induce or amplify an inflammatory process through many of the same cellular and molecular pathways conventionally utilized by immune cells mediating IBD. The aim of this article is to review data on the existence of platelet dysfunction in IBD, substantiate platelets' inflammatory potential, discuss the implications of abnormal platelet activity for chronic intestinal inflammation, and consider the potential benefits of platelet modulation for treatment of IBD.

Platelet activation in heart transplant recipients

An inappropriate and persistent immune activation has been suggested to contribute to long-term mortality and morbidity after heart transplantation. Several lines of evidence suggest that platelets do not only promote thrombus formation, but also act as inflammatory cells. In the present study, we investigated if long-time survivors of heart transplantation (mean time since transplantation 6.5 yr) were characterized by enhanced platelet activation as assessed by different experimental approaches. Our main findings when comparing heart transplant recipients (n = 52) and age- and sex-matched healthy controls (n = 38) were: (i) platelets from heart transplant recipients showed enhanced expression of both P-selectin and CD63 as assessed by flow cytometry; (ii) platelets from these patients also contained significantly increased levels of soluble CD40 ligand and tended to release higher levels of this cytokine upon SFLLRN stimulation as assessed by enzyme immunoassay; (iii) heart transplant recipients had increased levels of soluble P-selectin in platelet-free plasma; and (iv) the enhanced platelet activation after heart transplantation was most pronounced in those with concomitant hypertension. These findings suggest that long-term survivors of heart transplantation are characterized by enhanced activation of platelets, possibly contributing to the persistent immune activation and clinical complications in these patients.

Differential response of platelets to chemokines: RANTES non-competitively inhibits stimulatory effect of SDF-1 alpha

BACKGROUND

Among the chemokines related to CXC and CC receptor groups and released from platelets, leukocytes and endothelial cells, SDF-1, TARC and MDC have been found to be platelet agonists. Platelets do not contain SDF-1 alpha. In contrast, RANTES is constitutively present in platelet alpha-granules and released upon platelet activation.

OBJECTIVES

To study a possible role of RANTES as a modulator of SDF-1 alpha effect on platelets, in relation to CXCR4 and various CC receptors.

METHODS

CXCR-4 (CXCL12) receptor expression and platelet activation were evaluated by flow cytometry, platelet deposition was studied by cone and plate(let) analyzer, and platelet aggregation by turbidometric aggregometry.

RESULTS

Flow cytometry studies revealed similar expression of CXCR-4, the specific receptor of SDF-1 alpha on intact, inactivated, and activated platelets. Preincubation of platelets with RANTES affected neither CXCR-4 expression, nor SDF-1 alpha binding to the platelet membrane. In the presence of fibrinogen, SDF-1 alpha activated gel-filtered platelets. RANTES did not activate platelets, but substantially (by 70%) inhibited SDF-1 alpha-induced fibrinogen binding. Similarly, RANTES abrogated the promoting effect of SDF-1 alpha on whole blood platelet adhesion to endothelial cell monolayer under venous flow conditions. In platelet-rich plasma, RANTES moderately inhibited SDF-1 alpha-induced platelet aggregation, while it did not affect aggregation induced by thrombin-receptor activation peptide, adenosine diphosphate, or phorbol 12-myristate 13-acetate. A synergistic inhibitory effect of RANTES and prostaglandin E1 used at subthreshold concentrations, on SDF-1 alpha-induced aggregation and SDF-1 alpha-induced fibrinogen binding to platelets was observed, which may suggest involvement of RANTES in a cAMP-dependent signal transduction pathway.

CONCLUSIONS

RANTES non-competitively inhibits activation of platelets by SDF-1 alpha, and thus may play a regulatory role in platelet response to inflammation.

Of blood and guts: association between Helicobacter pylori and the gastric microcirculation

The relative importance of acid in Helicobacter pylori (H. pylori) ulcer pathogenesis is in doubt, with possibilities existing that other contributing factors may be involved. Vascular insufficiency may lead to the development of ischemic lesions or ulcers within the gastric mucosa. H. pylori produces a striking inflammatory response following infection and one of the major components of gastrointestinal inflammation is alterations in the vascular structure and function. This suggests that the microcirculation may be a key target of H. pylori-released factors. Recent evidence has accumulated to suggest that H. pylori can affect a number of microcirculatory variables including blood flow, leukocyte activity and also induce changes in the endothelial lining of the vessels themselves. The majority of these findings have been described by employing the technique of fluorescent in vivo microscopy, which allows direct, dynamic and real time observations of the microcirculation to be made. A universal feature of these experimental studies has been the formation of circulating or adherent platelet aggregates. It is now recognized that platelets participate in the inflammatory response by acting as a potent source of inflammatory mediators and modulating the activity of other inflammatory cells. Circulation of platelet emboli may be of cause for concern, especially as a number of studies have demonstrated an association between H. pylori infection and coronary heart disease. The present review highlights the major findings from these studies and proposes an important role for the gastric microcirculation in the pathophysiology of H. pylori-induced injury.

Efficacy of serotonin receptor blocker for symptomatic lumbar disc herniation

Serotonin is one of the chemical mediators associated with nerve root inflammation and sciatic symptoms in lumbar disc herniation. The efficacy of serotonin 5-HT(2A) receptor blocker was examined in 44 patients with symptomatic lumbar disc herniation. A selective 5-HT(2A) receptor blocker (sarpogrelate hydroxychloride) was administered orally at a dose of 300 mg per day for 2 weeks. Visual analog scales of low back pain, sciatic pain, and numbness were significantly improved after the administration of the serotonin 5-HT(2A) receptor blocker. Clinical results were good (> 50% pain relief) in 23 patients, fair (25%-50% pain relief) in five patients, and poor (< 25% of pain relief) in 16 patients. Nineteen patients eventually required surgery because of muscle weakness or cauda equina symptoms. The effect of 5-HT(2A) blocker was good in 64% of patients who had uncontained disc herniation, whereas all patients with contained disc herniation had fair or poor results. Patients with uncontained disc herniation responded more favorably to the 5-HT(2A) blocker treatment than patients with contained disc herniation. A 5-HT(2A) blocker has the potential to block the cascade of acute nerve root inflammation and to alleviate symptoms in lumbar disc herniation.

5-HT2A receptor subtype in the peripheral branch of sensory fibers is involved in the potentiation of inflammatory pain in rats

One of the major serotonin (5-HT) receptor subtypes expressed in the rat dorsal root ganglion (DRG) neurons is the 5-HT2A receptor. We have previously shown that 5-HT2A receptors in the peripheral sensory terminals are responsible for 5-HT-induced pain and hyperalgesia. In the present study, we characterized neurons expressing 5-HT2A receptors in the rat DRG neurons by means of in situ hybridization, immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR) and behavioral tests. In situ hybridization on consecutive sections revealed that 5-HT2A receptor mRNA is colocalized with calcitonin-gene related peptide (CGRP) mRNA (100/104; 96.2%) but not with c-Ret mRNA (1/115; 0.9%). Signals for 5-HT2A receptor mRNA were found in 9.4 +/- 2.2% of normal DRG (L5) neurons, most of which were small to medium in size. Four days of complete Freund's adjuvant-induced inflammation of the hindpaw doubled the incidence of 5-HT2A receptor mRNA-expressing neurons to 19.3 +/- 2.8%. The level of 5-HT2A receptor mRNA in DRGs of normal and various pathological conditions was then determined by RT-PCR. The level was up-regulated by peripheral inflammation, but not by axotomy or chronic constriction of the peripheral nerve. Systemic administration of 5-HT2A receptor antagonist (Sarpogrelate HCI) produced analgesic effects on thermal hyperalgesia caused by peripheral inflammation, but failed to attenuate thermal hyperalgesia in chronic constriction injury model. These findings suggest that 5-HT2A receptors are mainly expressed in CGRP-synthesizing small DRG neurons and may be involved in the potentiation of inflammatory pain in the periphery.

Are thrombocytes and platelets true phagocytes?

Thrombocytes and platelets, beyond their primary function in hemostasis, seem to play an active role in inflammation. As regards their phagocytic ability, the results to date are confusing, incomplete, and somewhat contradictory. Whereas the interaction of avian thrombocytes or mammalian platelets with bacteria both in vitro and in vivo has received wide attention, almost no information exists on the topic in "lower" vertebrates. The aim of this work is to review the available information on the phagocytic properties of thrombocytes and platelets. Particular attention is payed to the ontogeny of these cells, the soluble factors involved in the inflammatory process derived from them, and their interaction with particulate material, mainly with bacteria.