Increased soluble P-selectin levels in hepatitis C virus-related chronic hepatitis: correlation with viral load

Platelet Activation is Upregulated in Cirrhotic Patients with Portal Vein Thrombosis

OBJECTIVE

 Platelet plays a key role in thrombosis formation, especially that the alteration of platelet function may influence the thrombosis development. This study aimed to investigate platelet function alterations in the formation of portal vein thrombosis (PVT) in cirrhosis.

METHODS

 Cirrhotic patients admitted to The First Affiliated Hospital of Soochow University between October 2021 and April 2023 were recruited and divided into PVT and non-PVT groups according to radiological results. Clinical parameters and prognosis were also collected and assessed to identify potential risk factors. Flow cytometry was used to detect the expression of CD62p, CD63, monocyte-platelet aggregates (MPAs), neutrophil-platelet aggregates (NPAs), and von Willebrand factor antigen (vWF-Ag) to evaluate platelet activation and adhesion function.

RESULTS

 A total of 145 subjects were enrolled in our study including 60 cirrhotic PVT patients, 60 cirrhotic non-PVT patients, and 25 healthy volunteers. Multivariate analysis suggested that esophageal gastric varices, splenectomy, and D-dimer were independent risk factors for PVT pathogenesis in cirrhosis. The vWF-Ag expression level was reduced in the PVT group compared with the non-PVT group (p = 0.046) but was not an independent risk factor for PVT formation pathogenesis. The expression of CD41+CD62p+ and CD41+CD63+ platelets in the PVT group was significantly elevated compared with that in the non-PVT group (p < 0.05). There were no significant differences in MPAs and NPAs between the two cirrhotic groups. Subgroup analysis showed that the mean fluorescence intensity (MFI) of CD62p and CD63 was associated with portal hypertension-related complications (p = 0.008, p < 0.001), and CD63 MFI was significantly associated with thrombosis burden (p = 0.019). CD41+CD62p+ and CD41+CD63+ platelets as well as MPAs and NPAs were highly expressed in the splenectomy group compared with those in the nonsplenectomy group in cirrhotic patients (p < 0.05). Positive correlations were found between CD62p MFI and CD63 MFI, MPAs and NPAs (r = 0.642, p < 0.001; r = 0.378, p = 0.003; r = 0.430, p < 0.001). In addition, platelet counts were also correlated with MPAs (r = 0.556, p < 0.001) and NPAs (r = 0.467, p < 0.001). Cirrhotic patients with PVT had higher mortality and were more likely to experience portal hypertension-related complications in the prognostic analysis (p < 0.05).

CONCLUSION

 Highly activated platelet function exists in patients with cirrhosis, and platelet activation was elevated during PVT formation, suggesting that activated platelets may participate in the formation of PVT in patients with cirrhosis.

"Ultrastructural changes of platelets in COVID-19 and chronic viral hepatitis patients "

Platelet-viral interactions are evolving as a new concern. Coagulation disorder is a major consequence of the COVID-19 infection. In chronic hepatitis virus infections, defect in coagulation factors, thrombocytopenia and platelet function abnormalities are common. A SARS-CoV-2 infection on top of chronic viral hepatitis infection can be common in areas where viral hepatitis is endemic. Here, we investigate the platelet ultrastructural changes and estimate the serum platelet factor-4 (PF-4), ferritin, CRP, and D-dimer in COVID-19 patients (n = 60), COVID-19 patients with associated chronic viral hepatitis (n = 20), and healthy subjects (n = 20). Ultrastructural changes were demonstrated in all test groups, denoting platelet activation. In chronic viral hepatitis patients, Platelet ultrastrustural apoptotic changes were also seen. Significantly high levels of PF-4 were confirmed in moderate and severe COVID-19 patients (P.value <0.001), with a cut off value of 17 ng/ml for predicting disease severity. A positive correlation of PF-4 with the level of serum ferritin, CRP, and D-dimer (p value < 0.001) was noted, while negatively correlated with platelet count and platelet granule count (p value < 0.001). In our study, chronic viral hepatitis patients presented mild COVID-19 signs, and their PF-4 level was comparable with the subgroup of mild COVID-19 infection. The platelet's critical role in COVID-19 coagulopathy and chronic viral hepatitis is evidenced by the ultrastructural changes and the high levels of PF4. Moreover, a dual viral infection poses a substantial burden on the platelets, necessitating close monitoring of the patient's coagulation profile.

Portal vein thrombosis in cirrhosis: A literature review

Portal Vein Thrombosis (PVT), a common complication of advanced liver disease, is defined as an obstruction of the portal vein due to thrombus formation that can extend to the superior mesenteric and splenic veins. It was believed that PVT occurred predominantly due to prothrombotic potential. However, recent studies have shown that decreased blood flow related to portal hypertension appears to increase PVT risk as per Virchow's triad. It is well known that there is a higher incidence of PVTs in cirrhosis with a higher MELD and Child Pugh score. The controversy for management of PVTs in cirrhotics lies in the individualized assessment of risks versus benefits of anticoagulation, since these patients have a complex hemostatic profile with both bleeding and procoagulant propensities. In this review, we will systematically compile the etiology, pathophysiology, clinical features, and management of portal vein thrombosis in cirrhosis.

Al-buhadiliy A, De Waard M, Sabatier JM, Khan Khalil AA, Saad HM, Batiha GES. Role of Neuropilin 1 in COVID-19 Patients with Acute Ischemic Stroke

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection can trigger the adaptive and innate immune responses, leading to uncontrolled inflammatory reactions and associated local and systematic tissue damage, along with thromboembolic disorders that may increase the risk of acute ischemic stroke (AIS) in COVID-19 patients. The neuropilin (NRP-1) which is a co-receptor for the vascular endothelial growth factor (VEGF), integrins, and plexins, is involved in the pathogenesis of AIS. NRP-1 is also regarded as a co-receptor for the entry of SARS-CoV-2 and facilitates its entry into the brain through the olfactory epithelium. NRP-1 is regarded as a cofactor for binding of SARS-CoV-2 with angiotensin-converting enzyme 2 (ACE2), since the absence of ACE2 reduces SARS-CoV-2 infectivity even in presence of NRP-1. Therefore, the aim of the present study was to clarify the potential role of NRP-1 in COVID-19 patients with AIS. SARS-CoV-2 may transmit to the brain through NRP-1 in the olfactory epithelium of the nasal cavity, leading to different neurological disorders, and therefore about 45% of COVID-19 patients had neurological manifestations. NRP-1 has the potential capability to attenuate neuroinflammation, blood-brain barrier (BBB) permeability, cerebral endothelial dysfunction (ED), and neuronal dysfunction that are uncommon in COVID-19 with neurological involvement, including AIS. Similarly, high NRP-1 serum level is linked with ED, oxidative stress, and the risk of pulmonary thrombosis in patients with severe COVID-19, suggesting a compensatory mechanism to overcome immuno-inflammatory disorders. In conclusion, NRP-1 has an important role in the pathogenesis of COVID-19 and AIS, and could be the potential biomarker linking the development of AIS in COVID-19. The present findings cannot provide a final conclusion, and thus in silico, experimental, in vitro, in vivo, preclinical, and clinical studies are recommended to confirm the potential role of NRP-1 in COVID-19, and to elucidate the pharmacological role of NRP-1 receptor agonists and antagonists in COVID-19.

The Pathophysiology of Portal Vein Thrombosis in Cirrhosis: Getting Deeper into Virchow's Triad

Portal vein thrombosis (PVT) is a common complication among patients with cirrhosis. However, its pathophysiology is not well established and there are currently very few predictive factors, none of which are actually useful, from a clinical perspective. The contribution of each of the vertices of Virchow’s triad, e.g., blood hypercoagulability, blood flow, and portal vein endothelial damage in the development of PVT is not clear. In this review, we aim to recapitulate the latest studies on the field of PVT development in order to understand its mechanisms and discuss some of the future directions in the study of this important complication of cirrhosis.

Blood platelet function abnormalities in cirrhotic patients with esophageal varices in relation to the variceal bleeding history

Objective: The study aimed at assessing the effect of thrombocytopenia and platelet function abnormalities on the occurrence of variceal bleeding in patients with cirrhosis. Methods: The results of impedance aggregometry, von Willebrand factor antigen level and thromboelastometry (TEM) with and without the addition of a platelet inhibitor (FIBTEM^®, EXTEM^® test, respectively) were compared in two patient groups: Group 1 (n = 32) - patients with moderate or large esophageal or gastric varices, who had never had symptoms of acute gastrointestinal bleeding and Group 2 (n = 26) - patients with history of variceal bleeding. Results: Standard clotting test indicated more hypocoagulable profile in Group 2 compared to Group 1. However, no differences in any TEM component were observed between groups in EXTEM^® test. The contribution of platelets to clot strength was significantly higher in Group 2 than in Group 1 [PLT% = 74.2 (67.5-80.4) versus 68.8 (63.7-76.5) %; p = .039]. The aggregation index was also higher in Group 2 compared to Group 1, although not statistically significant [% of healthy = 96.9 (73.2-140.1) versus 67.6 (52.5-118.8) %, p = .195]. No differences in vWF antigen levels were observed between groups. Conclusions: The results of thromboelastometry and aggregometry indicate increased contribution of platelets in clot formation in patients with a history of variceal bleeding compared to cirrhotic patients who never bled. Comparable effectiveness of hemostasis in both groups is most likely associated with the compensatory role of platelets. Increased platelet activity in this group of patients is probably due to a mechanism independent of the von Willebrand factor antigen level.

Hepatitis C virus and atherosclerosis: A legacy after virologic cure?

Hepatitis C virus (HCV) is a major pathogen with approximately 3% of the world's population (over 170 million) infected. Epidemiological studies have shown HCV is associated with an increased risk of cardiovascular and cerebrovascular mortality as well as peripheral arterial disease. This is despite HCV inducing an ostensibly favourable lipid profile with accompanying low classical risk score for atherosclerosis (AS). We discuss possible factors involved in the aetiopathogenesis of atherosclerosis in chronic HCV and hypothesise that an important mechanism underlying the development of AS is the presence of circulating low-density immune complexes that induce an inflammatory response. We suggest that HCV particles may be inducing an antibody response to lipoproteins present in the lipoviral particles and sub-viral particles - a concept similar to the more general 'autoantibody' response to modified LDL. After virologic cure some AS risk factors will recede but an increase in serum cholesterol could result in progression of early atherosclerotic lesions, leaving a legacy from persistent HCV infection that has clinical and therapeutic implications.

Thromboelastographic reference ranges for a cirrhotic patient population undergoing liver transplantation

AIM

To describe the thromboelastography (TEG) “reference” values within a population of liver transplant (LT) candidates that underline the differences from healthy patients.

METHODS

Between 2000 and 2013, 261 liver transplant patients with a model for end-stage liver disease (MELD) score between 15 and 40 were studied. In particular the adult patients (aged 18-70 years) underwent to a first LT with a MELD score between 15 and 40 were included, while all patients with acute liver failure, congenital bleeding disorders, and anticoagulant and/or antiplatelet drug use were excluded. In this population of cirrhotic patients, preoperative haematological and coagulation laboratory tests were collected, and the pretransplant thromboelastographic parameters were studied and compared with the parameters measured in a previously studied population of 40 healthy subjects. The basal TEG parameters analysed in the cirrhotic population of liver candidates were as follows: Reaction time (r), coagulation time (k), Angle-Rate of polymerization of clot (αAngle), Maximum strenght of clot (MA), Amplitudes of the TEG tracing at 30 min and 60 min after MA is measured (A30 and A60), and Fibrinolysis at 30 and 60 min after MA (Ly30 and Ly60). The possible correlation between the distribution of the reference range and the gender, age, MELD score (higher or lower than 20) and indications for transplantation (liver pathology) were also investigated. In particular, a MELD cut-off value of 20 was chosen to verify the possible correlation between the thromboelastographic reference range and MELD score.

RESULTS

Most of the TEG reference values from patients with end-stage liver disease were significantly different from those measured in the healthy population and were outside the suggested normal ranges in up to 79.3% of subjects. Wide differences were found among all TEG variables, including r (41.5% of the values), k (48.6%), α (43.7%), MA (79.3%), A30 (74.4%) and A60 (80.9%), indicating a prevailing trend to hypocoagulability. The differences between the mean TEG values obtained from healthy subjects and the cirrhotic population were statistically significant for r (P = 0.039), k (P < 0.001), MA (P < 0.001), A30 (P < 0.001), A60 (P < 0.001) and Ly60 (P = 0.038), indicating slower and less stable clot formation in the cirrhotic patients. In the cirrhotic population, 9.5% of patients had an r value shorter than normal, indicating a tendency for faster clot formation. Within the cirrhotic patient population, gender, age and the presence of hepatocellular carcinoma or alcoholic cirrhosis were not significantly associated with greater clot firmness or enhanced whole blood clot formation, whereas greater clot strength was associated with a MELD score < 20, hepatitis C virus and cholestatic-related cirrhosis (P < 0.001; P = 0.013; P < 0.001).

CONCLUSION

The range and distribution of TEG values in cirrhotic patients differ from those of healthy subjects, suggesting that a specific thromboelastographic reference range is required for liver transplant candidates.

P selectins and immunological profiles in HCV and Schistosoma mansoni induced chronic liver disease

Background

Hepatitis C virus (HCV) and Schistosoma mansoni are major causes of chronic liver disease (CLD) in which immune alteration is common. Recent studies suggested that certain platelets and lymphocytes activation markers may have an impact on progression of CLD. This study aimed to evaluate the potential of platelets and lymphocytes activation molecules expression on the pathogenesis of CLD in distinct or concomitant chronic HCV and schistosomiasis mansoni infections.

Methods

The study populations were divided into group-I: patients with chronic schistosomiasis mansoni, group-II: HCV patients without cirrhosis, group-III: patients with combined liver diseases without cirrhosis, group-IV: patients with chronic HCV and liver cirrhosis and group-V: Age and sex matched healthy individuals as normal controls. All groups were subjected to full clinical evaluation, ELISA anti-HCV antibodies screening, parasitological examination for diagnosing S. mansoni and flow cytometry for lymphocyte (CD3, CD4, CD8, CD19, CD22, & CD56) and platelets activation (CD41, CD42 & CD62P (P- selectins)) markers.

Results

The platelet count was significantly decreased in HCV and/or S. mansoni patients. The total T-lymphocytes and T-helper cells were significantly reduced, while T-cytotoxics were increased. The patients possessed a significantly higher platelets activation marker; CD62P (P-selectins) and higher mean fluorescent intensity (MFI) positivity. There were considerable correlations between platelets count and both of CD62P and MFI.

Conclusion

Our Findings suggest an increased expression of certain platelets and lymphocytes activation markers in chronic HCV and S. mansoni induced CLD that may have a role in disease progression.

Patients with liver cirrhosis suffer from primary haemostatic defects? Fact or fiction?

Patients with cirrhosis can have abnormalities in laboratory tests reflecting changes in primary haemostasis, including bleeding time, platelet function tests, markers of platelet activation, and platelet count. Such changes have been considered particularly relevant in the bleeding complications that occur in cirrhosis. However, several studies have shown that routine diagnostic tests, such as platelet count, bleeding time, PFA-100, thromboelastography are not clinically useful to stratify bleeding risk in patients with cirrhosis. Moreover, treatments used to increase platelet count or to modulate platelet function could potentially do harm. Consequently the optimal management of bleeding complications is still a matter of discussion. Moreover, in the last two decades there has been an increased recognition that not only bleeding but also thrombosis complicates the clinical course of cirrhosis. Thus, we performed a literature search looking at publications studying both qualitative and quantitative aspects of platelet function to verify which primary haemostasis defects occur in cirrhosis. In addition, we evaluated the contribution of qualitative and quantitative aspects of platelet function to the clinical outcome in cirrhosis and their therapeutic management according to the data available in the literature. From the detailed analysis of the literature, it appears clear that primary haemostasis may not be defective in cirrhosis, and a low platelet count should not necessarily be considered as an automatic index of an increased risk of bleeding. Conversely, caution should be observed in patients with severe thrombocytopenia where its correction is advised if bleeding occurs and before invasive diagnostic and therapeutic procedures.

Platelet activation and vascular endothelial growth factor 165 release in hepatocellular cancer

BACKGROUND

Vascular endothelial growth factor (VEGF₁₆₅) is stored, transported and released by platelets. Platelet functional abnormalities have been described in patients with hepatocellular carcinoma (HCC). Thus, this study was designed to investigate the behavior of VEGF₁₆₅ with respect to platelet activation in HCC.

METHODS

Plasma and serum VEGF₁₆₅ and plasma sP-selectin levels were analyzed in patients with HCC (n=70) or cirrhosis (n=45) and control subjects (n=70). Given the thrombocytopenia that characterizes both HCC and cirrhotic patients, plasma VEGF₁₆₅ and sP-selectin as well as serum VEGF (plt-VEGF₁₆₅-load) levels were normalized by platelet counts.

RESULTS

Median concentrations of plasma VEGF₁₆₅/platelet (p=0.002) and sP-selectin/platelet (p<0.0001) were higher in HCC or cirrhotic patients compared to controls. Moreover, sP-selectin/platelet was the only independent variable predictive of plasma VEGF₁₆₅/platelet at multivariate analysis (p<0.0001). Conversely, plt-VEGF₁₆₅-load correlated with tumor diameter (p<0.05) but not with sP-selectin/platelet and was an independent predictor for 5year overall survival (p=0.012).

CONCLUSIONS

The results obtained are suggestive for VEGF₁₆₅ release by tumor in HCC. It is plt-VEGF₁₆₅-load, but not plasma VEGF₁₆₅ or serum VEGF₁₆₅ that is an independent predictor for overall survival of HCC patients.

Monocyte-platelet aggregates and platelet micro-particles in patients with post-hepatitic liver cirrhosis

INTRODUCTION

Monocytes are the cells that play a crucial role in the pathogenesis of liver damage and liver cirrhosis (LC), and as platelets, by connecting hemostasis and inflammatory processes, participate in pathogenesis of chronic liver diseases, we aimed to investigate the presence of monocyte-platelet aggregates and platelet micro-particles (PMPs) and their role in LC.

PATIENTS AND METHODS

The study included 60 patients with post-hepatitic LC and 20 healthy controls. Activated monocytes (CD11b, HLA-DR, CD14, CD16), monocyte-platelet aggregates (CD41/CD14), activated platelets (CD41/CD62) and PMPs were analyzed by flow cytometry. Their relations to the clinical and laboratory data were assessed in the studied group.

RESULTS

Patients with LC had higher levels of activated platelets, activated monocytes and monocyte-platelet aggregations as compared to healthy controls. PMPs percentage showed no significant differences between patients and controls but significantly increased in both patients with no bleeding and patients with splenomegaly compared to patients without. All studied markers showed no significant differences between patients with thrombocytopenia and those with normal platelet counts and also between patients with different disease stages. Positive correlations between monocyte-platelet aggregates and both activated platelets and monocytes were demonstrated. There were significant negative correlations between PMPs and both age and prothrombin time among patients.

CONCLUSIONS

The stage of post-hepatitic LC is not the only factor that affects the level of activated platelets, activated monocytes and monocyte-platelet aggregates. PMPs have no influence on thrombocytopenia but may have the potential to influence the progression of clotting activity in LC.

Association of hepatitis C virus seropositivity with inflammatory markers and heart failure in persons with coronary heart disease: data from the Heart and Soul study

BACKGROUND

How hepatitis C virus (HCV) affects coronary heart disease (CHD) risk factors and outcomes is largely unknown.

METHODS AND RESULTS

Among a cohort of patients with stable CHD, we examined the association between HCV seropositivity and levels of inflammatory markers (C-reactive protein [CRP], fibrinogen, interleukin-6, and tumor necrosis factor [TNF]-alpha) and risk for the following outcomes: death, cardiovascular (CV) events, and heart failure events. A total of 84 (8.6%) participants were found to be seropositive for HCV. HCV-seropositive patients were found to have significantly lower adjusted mean levels of CRP (2.6 vs. 4.4; P < .01) and fibrinogen (340 vs. 398; P < .01), but higher levels of TNF-alpha (7.1 vs. 4.8; P < .01). Age-adjusted rates for HCV seropositive vs. seronegative were as follows: death 93 vs. 42/1,000p-y (P < .01), CV events 62 vs. 40 (P=.13), and heart failure 76 vs. 29 (P < .01). After adjustment for demographic and clinical factors, HCV remained significantly associated with an increased risk for heart failure events (HR=2.13; 95% CI: 1.19-3.80).

CONCLUSIONS

In this cohort with CHD, HCV seropositive participants had higher rates of death, CV events, and heart failure hospitalizations during follow-up. After adjustment for CV risk factors, HCV seropositivity remained independently associated with risk for heart failure events.

Review article: blood platelet number and function in chronic liver disease and cirrhosis

BACKGROUND

The liver plays a central role in coagulation and fibrinolysis but is also closely intertwined with the function and number of blood platelets.

AIM

To describe and integrate all literature concerning blood platelets and liver disease by performing a thorough literature research.

METHODS

A thorough literature research on 'blood platelets' and 'liver disease' was performed.

RESULTS

Thrombocytopenia is a marked feature of chronic liver disease and cirrhosis. Traditionally, this thrombocytopenia was attributed to passive platelet sequestration in the spleen. More recent insights suggest an increased platelet breakdown and to a lesser extent decreased platelet production plays a more important role. Besides the reduction in number, other studies suggest functional platelet defects. This platelet dysfunction is probably both intrinsic to the platelets and secondary to soluble plasma factors. It reflects not only a decrease in aggregability, but also an activation of the intrinsic inhibitory pathways. The net effect, finally, is a decreased platelet function in the various types of chronic liver diseases and cirrhosis. Finally, recent data suggest that platelets are not only affected by but can also contribute to the liver disease process, as for instance, in viral hepatitis and cholestatic liver disease.

CONCLUSION

Platelet research in liver disease is a growing area of investigation and could provide new pathophysiological insights.

Does the periodontal health of thalassemia major patients have an impact on the blood lipid profiles? A preliminary report

Cardiac symptoms and premature death from cardiac causes are still suggested to be a major problem in thalassemic patients. One of the main reasons for the cardiovascular events in thalassemia major (TM) patients has suggested having iron overload, in addition to other reasons such as hypoxia, abnormal lipoproteins levels, atherosclerotic conditions, etc. This study aims to investigate whether the periodontal health has an impact on the blood lipid levels. Twenty-four TM patients and sex-matched controls (C) enrolled to this study. The measurements of the periodontal parameters (gingival index, plaque index, bleeding on probing, probing depth, and clinical attachment level) were recorded. Besides, in venous blood samples the lipid profile was investigated. All of the periodontal parameters were significantly higher in TM group than in C group (P<0.05). Triglyceride and cholesterol/high density lipoprotein ratio had significant positive correlations with the periodontal parameters (P<0.05). Multiple regression analyses present significant associations between gingival index, plaque index scores, and the cholesterol/high density lipoprotein ratio (P<0.001). Our study results showed that the lipid profile of TM patients might be affected by their periodontal health. Further studies are needed to determine the lipid profile involvement magnitude and the cardiovascular disease risk caused by the periodontal health of TM patients.

Elevation of rat plasma P-selectin in acute lung injury

Acute lung injury in the rat caused by intravenous (i.v.) infusion of cobra venom factor (CVF) or lipopolysaccharide (LPS) is mediated by P-selectin-dependent neutrophil infiltration into the lung. In these lung injury models, P-selectin expression is induced on lung vascular endothelial cells after the CVF or LPS infusion, suggesting soluble P-selectin derived from inflamed sites might also be elevated. Here we established a sensitive enzyme-linked immunosorbent assay (ELISA) to measure soluble P-selectin in plasma, a potential marker of lung injury. Nine anti-rat P-selectin monoclonal antibodies that we established previously were first classified into 5 groups based on real-time biospecific interaction analyses, and used to develop a sandwich ELISA for accurately measuring the amount of soluble P-selectin in plasma. We then used this ELISA to measure the plasma P-selectin levels in Long Evans, Wistar, and Sprague-Dawley rats after the i.v. infusion of CVF or LPS. The elevation in P-selectin levels was significantly different among the strains, but it consistently correlated with the extent of lung inflammation, measured by myeloperoxidase levels in the lung tissues. Thus, our results indicate that the soluble P-selectin in plasma could serve as a sensitive biomarker reflecting lung inflammation, which is of clinical importance for detecting and preventing severe lung injury.

Differential expression of genes encoding CD30L and P-selectin in cattle with Johne's disease: Progress toward a diagnostic gene expression signature

Mycobacterium avium subspecies paratuberculosis (Mycobacterium paratuberculosis), the causative agent of paratuberculosis (paraTB) or Johne's disease in ruminants, is a health problem for the global cattle industry with significant economic losses related to decreased milk production and reduced fertility. Commonly paraTB in cattle is diagnosed by antibody detection by serum enzyme-linked immunosorbent assay (ELISA), by detection of the pathogen by cultivation of individual faecal samples, or by in vitro measurement of cell mediated immune responses using the IFN-gamma test. There is an ongoing need for developing new diagnostic approaches as all currently available diagnostic tests for paraTB may fail to detect sub-clinical infection. We used cDNA microarrays to simultaneously measure expression of over 1300 host genes to help identify a subset of gene expression changes that might provide a unique gene expression signature for paraTB infection. In the present study, non-stimulated leukocytes isolated from 10 sub-clinical paraTB infected cows were examined for genes being expressed at significantly different levels than in similar cells from control cows with the same herd background. We included cattle (Holstein) from two locations (Denmark and USA) for the microarray experiment. Our results indicate that expression profiles of at least 52 genes are different in leukocytes from M. paratuberculosis infected cattle compared to control cattle. Gene expression differences were verified by quantitative real-time reverse transcriptase polymerase chain reactions (qRT-PCR) on the same group of cattle (Holstein) used for the microarray experiment. In order to assess the generality of the observed gene expression, a second and different group of cattle (Jersey) was also examined using qRT-PCR. Out of the seven genes selected for qRT-PCR, CD30 ligand (CD30L) and P-selectin were consistently differentially expressed in freshly isolated leukocytes from paraTB infected and control animals of both breeds of cattle. Although further work is clearly needed to develop a more complete gene expression signature specific for paraTB, our results demonstrate that a subset of genes in leukocytes are consistently expressed at different levels, depending upon M. paratuberculosis infection status.

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.

Plasma P-selectin levels are elevated in patients with chronic liver disease

P-selectin is a leukocyte receptor and platelet activation marker that has been shown to be involved in thrombogenesis as well as bleeding disorders and may represent a possible link between inflammation and thrombosis. In animal models, high plasma levels correlated with a procoagulant tendency. In acute liver damage models such as hepatic ischaemia-reperfusion-injury, P-selectin was found to be a key mediator of liver injury. In order to investigate the clinical and pathogenetic role of P-selectin in chronic liver diseases, plasma P-selectin levels were measured in 111 patients with chronic liver diseases. P-Selectin was significantly elevated in patients (median 56 ng/ml, range 0-180) compared with controls (n = 38, median 20 ng/ml, range 3.3-42, P < 0.001). Current clinical bleeding symptoms were common, whereas thrombotic events occurred rarely. P-selectin levels were not associated with haemorrhagic or thromboembolic complications. P-selectin correlated with platelet and white-blood-cell counts, but not with endothelial injury markers thrombomodulin and tissue factor or coagulation factors. Interestingly, P-selectin levels were not associated with Child's stage of cirrhosis or disease aetiology, but were generally elevated in chronic liver diseases. Severe hepatic leukocyte infiltration in liver histology was associated with a tendency towards higher P-selectin levels. In line with its role in acute liver damage, P-selectin elevation in chronic liver disease may suggest a possible pathogenetic role in the course of liver cirrhosis.