R643G polymorphism in PECAM-1 influences transendothelial migration of monocytes and is associated with progression of CHD and CHD events

Prognostic Factors for Restenosis of Superficial Femoral Artery after Endovascular Treatment

High incidence of superficial femoral artery (SFA) restenosis after percutaneous transluminal angioplasty (PTA) poses a persistent challenge in peripheral arterial disease (PAD) treatment. We studied how the patients' and lesions' characteristics, thrombin generation, overall haemostatic potential (OHP), and single nucleotide polymorphisms (SNPs) of the NR4A2 and PECAM1 genes affected the likelihood of restenosis. In total, 206 consecutive PAD patients with limiting intermittent claudication due to SFA stenosis who were treated with balloon angioplasty with bailout stenting when necessary were included. Patients' clinical status and patency of the treated arterial segment on ultrasound examination were assessed 1, 6, and 12 months after the procedure. Restenosis occurred in 45% of patients, with less than 20% of all patients experiencing symptoms. In the multivariate analysis, predictors of restenosis proved to be poor infrapopliteal runoff, higher lesion complexity, absence of treated arterial hypertension, delayed lag phase in thrombin generation, and higher contribution of plasma extracellular vesicles to thrombin concentration. Poor infrapopliteal runoff increased the risk of restenosis in the first 6 months, but not later. The negative effect of poor infrapopliteal runoff on SFA patency opens questions about the potential benefits of simultaneous revascularisation of below-knee arteries along with SFA revascularisation.

Endothelial Barrier Function and Leukocyte Transmigration in Atherosclerosis

The vascular endothelium is a highly specialized barrier that controls passage of fluids and migration of cells from the lumen into the vessel wall. Endothelial cells assist leukocytes to extravasate and despite the variety in the specific mechanisms utilized by different leukocytes to cross different vascular beds, there is a general principle of capture, rolling, slow rolling, arrest, crawling, and ultimately diapedesis via a paracellular or transcellular route. In atherosclerosis, the barrier function of the endothelium is impaired leading to uncontrolled leukocyte extravasation and vascular leakage. This is also observed in the neovessels that grow into the atherosclerotic plaque leading to intraplaque hemorrhage and plaque destabilization. This review focuses on the vascular endothelial barrier function and the interaction between endothelial cells and leukocytes during transmigration. We will discuss the role of endothelial dysfunction, transendothelial migration of leukocytes and plaque angiogenesis in atherosclerosis.

Involvement of TIMP-1 in PECAM-1-mediated tumor dissemination

Platelet endothelial cell adhesion molecule-1 (PECAM-1) is expressed on the vascular endothelium and has been implicated in the late progression of metastatic tumors. The activity of PECAM-1 appears to be mediated by modulation of the tumor microenvironment (TME) and promotion of tumor cell proliferation, rather than through the stimulation of tumor angiogenesis. The present study aimed to extend those initial findings by indicating that the presence of functional PECAM-1 on the endothelium promotes a proliferative tumor cell phenotype in vivo, as well as in tumor cell (B16-F10 melanoma and 4T1 breast cancer cell lines) co-culture assays with mouse endothelial cells (ECs) or a surrogate EC line (REN-MP). The pro-proliferative effects were mediated by soluble endothelial-derived factors that were dependent on PECAM-1 homophilic ligand interactions, but which were independent of PECAM-1-dependent signaling. Further analysis of the conditioned media obtained from tumor/EC and tumor/REN-MP co-cultures identified TIMP metallopeptidase inhibitor-1 (TIMP-1) as a PECAM-1-regulated factor, the targeting of which in the tumor cell/REN-MP system inhibited tumor cell proliferation. In addition, TIMP-1 expression was decreased in metastatic tumors from the lungs of PECAM-1-null mice, thus providing evidence of the in vivo significance of co-culture studies. Taken together, these studies indicated that endothelial PECAM-1, through PECAM-1-dependent homophilic binding interactions, may induce release of TIMP-1 from the endothelium into the TME, thus leading to increased tumor cell proliferation.

Association of PECAM-1 Gene Polymorphisms with Kawasaki Disease in Chinese Children

Kawasaki disease (KD) is an acute systemic vasculitis complicated by development of coronary artery lesions. PECAM-1 is a kind of cell adhesion molecule, which plays an important role in coronary artery disease. The relationship between PECAM-1 gene polymorphisms and their susceptibility to Kawasaki diseases (KD) is still unclear. In our study, we examined the PECAM-1 gene polymorphisms in 44 KD patients and 59 healthy children and revealed the correlation of PECAM-1 gene polymorphisms in KD children with and without coronary artery lesions (CAL).

CD31 signals confer immune privilege to the vascular endothelium

Constitutive resistance to cell death induced by inflammatory stimuli activating the extrinsic pathway of apoptosis is a key feature of vascular endothelial cells (ECs). Although this property is central to the maintenance of the endothelial barrier during inflammation, the molecular mechanisms of EC protection from cell-extrinsic, proapoptotic stimuli have not been investigated. We show that the Ig-family member CD31, which is expressed by endothelial but not epithelial cells, is necessary to prevent EC death induced by TNF-α and cytotoxic T lymphocytes in vitro. Combined quantitative RT-PCR array and biochemical analysis show that, upon the engagement of the TNF receptor with TNF-α on ECs, CD31 becomes activated and, in turn, counteracts the proapoptotic transcriptional program induced by TNF-α via activation of the Erk/Akt pathway. Specifically, Akt activation by CD31 signals prevents the localization of the forkhead transcription factor FoxO3 to the nucleus, thus inhibiting transcription of the proapoptotic genes CD95/Fas and caspase 7 and de-repressing the expression of the antiapoptotic gene cFlar. Both CD31 intracellular immunoreceptor tyrosine-based inhibition motifs are required for its prosurvival function. In vivo, CD31 gene transfer is sufficient to recapitulate the cytoprotective mechanisms in CD31(-) pancreatic β cells, which become resistant to immune-mediated rejection when grafted in fully allogeneic recipients.

Mechanosignaling in the vasculature: emerging concepts in sensing, transduction and physiological responses

Cells are constantly exposed to mechanical forces that play a role in modulating cellular structure and function. The cardiovascular system experiences physical forces in the form of shear stress and stretch associated with blood flow and contraction, respectively. These forces are sensed by endothelial cells and cardiomyocytes and lead to responses that control vascular and cardiac homeostasis. This was highlighted at the Pan American Physiological Society meeting at Iguassu Falls, Brazil, in a symposium titled "Mechanosignaling in the Vasculature." This symposium presented recent research that showed the existence of a vital link between mechanosensing and downstream redox sensitive signaling cascades. This link helps to transduce and transmit the physical force into an observable physiological response. The speakers showcased how mechanosensors such as ion channels, membrane receptor kinases, adhesion molecules, and other cellular components transduce the force via redox signals (such as reactive oxygen species and nitric oxide) to receptors (transcription factors, growth factors, etc.). Receptor activated pathways then lead to cellular responses including cellular proliferation, contraction, and remodeling. These responses have major relevance to the physiology and pathophysiology of various cardiovascular diseases. Thus an understanding of the complex series of events, from the initial sensing through the final response, is essential for progress in this field. Overall, this symposium addressed some important emerging concepts in the field of mechanosignaling and the eventual pathophysiological responses.

Asn563Ser polymorphism of CD31/PECAM-1 is associated with atherosclerotic cerebral infarction in a southern Han population

BACKGROUND

CD31, also called platelet endothelial cell adhesion molecule-1 (PECAM-1), is thought to play a role in the pathological mechanisms of atherosclerosis. Leu125Val polymorphism and elevated plasma levels of soluble PECAM-1 (sPECAM-1) were found to be associated with cerebral infarction. Our aim was to investigate the association between the Asn563Ser polymorphism of CD31/PECAM-1, plasma level of sPECAM-1, and the risk of atherosclerotic cerebral infarction (ACI) in the southern Han population of the People's Republic of China.

SUBJECTS AND METHODS

A total of 147 subjects with ACI and 114 controls were enrolled in the study. The Asn563Ser CD31/PECAM-1 polymorphism was detected using the polymerase chain reaction-restriction fragment length polymorphism method. The plasma spECAM-1 level was measured using the enzyme-linked immunosorbent assay method.

RESULTS

In this study, statistically significant differences in Asn563Ser genotype and allele distribution were found between the cases and controls (P<0.05). Furthermore, logistic regression analysis showed that the GG genotype is associated with increase in ACI risk (odds ratio =4.862, P<0.001). The plasma level of sPECAM-1 was associated with ACI (odds ratio =1.431, P=0.038). In both the ACI and the control groups, the plasma sPECAM-1 level in subjects with the GG genotype was higher than that in subjects carrying the AA or GA genotype (P<0.05).

CONCLUSION

Our study showed that the Asn563Ser polymorphism of CD31/PECAM-1 gene and elevated plasma sPECAM-1 level are related to ACI risk in the southern Han population of People's Republic of China.

Cellular adhesion gene SELP is associated with rheumatoid arthritis and displays differential allelic expression

In rheumatoid arthritis (RA), a key event is infiltration of inflammatory immune cells into the synovial lining, possibly aggravated by dysregulation of cellular adhesion molecules. Therefore, single nucleotide polymorphisms of 14 genes involved in cellular adhesion processes (CAST, ITGA4, ITGB1, ITGB2, PECAM1, PTEN, PTPN11, PTPRC, PXN, SELE, SELP, SRC, TYK2, and VCAM1) were analyzed for association with RA. Association analysis was performed consecutively in three European RA family sample groups (Nfamilies = 407). Additionally, we investigated differential allelic expression, a possible functional consequence of genetic variants. SELP (selectin P, CD62P) SNP-allele rs6136-T was associated with risk for RA in two RA family sample groups as well as in global analysis of all three groups (ptotal = 0.003). This allele was also expressed preferentially (p<10-6) with a two- fold average increase in regulated samples. Differential expression is supported by data from Genevar MuTHER (p1 = 0.004; p2 = 0.0177). Evidence for influence of rs6136 on transcription factor binding was also found in silico and in public datasets reporting in vitro data. In summary, we found SELP rs6136-T to be associated with RA and with increased expression of SELP mRNA. SELP is located on the surface of endothelial cells and crucial for recruitment, adhesion, and migration of inflammatory cells into the joint. Genetically determined increased SELP expression levels might thus be a novel additional risk factor for RA.

An immunologist's guide to CD31 function in T-cells

Although it is expressed by all leukocytes, including T-, B-lymphocytes and dendritic cells, the immunoglobulin-like receptor CD31 is generally regarded by immunologists as a marker of endothelial cell lineage that lacks an established functional role in adaptive immunity. This perception has recently been challenged by studies that reveal a key role for this molecule in the regulation of T-cell homeostasis, effector function and trafficking. The complexity of the biological functions of CD31 results from the integration of its adhesive and signaling functions in both the immune and vascular systems. Signaling by means of CD31 is induced by homophilic engagement during the interactions of immune cells and is mediated by phosphatase recruitment or activation through immunoreceptor tyrosine inhibitory motifs (ITIMs) that are located in its cytoplasmic tail. Loss of CD31 function is associated with excessive immunoreactivity and susceptibility to cytotoxic killing. Here, we discuss recent findings that have brought to light a non-redundant, complex role for this molecule in the regulation of T-cell-mediated immune responses, with large impact on our understanding of immunity in health and disease.

Flow-dependent cellular mechanotransduction in atherosclerosis

Atherosclerosis depends on risk factors such as hyperlipidemia, smoking, hypertension and diabetes. Although these risk factors are relatively constant throughout the arterial circulation, atherosclerotic plaques occur at specific sites where flow patterns are disturbed, with lower overall magnitude and complex changes in speed and direction. Research over the past few decades has provided new insights into the cellular mechanisms of force transduction and how mechanical effects act in concert with conventional risk factors to mediate plaque formation and progression. This Commentary summarizes our current understanding of how mechanotransduction pathways synergize with conventional risk factors in atherosclerosis. We attempt to integrate cellular studies with animal and clinical data, and highlight major questions that need to be answered to develop more effective therapies.

Association of single nucleotide polymorphisms in the gene encoding platelet endothelial cell adhesion molecule-1 with the risk of myocardial infarction: a systematic review and meta-analysis

BACKGROUND

Single nucleotide polymorphisms (SNPs) within the platelet endothelial cell adhesion molecule-1 (PECAM-1) gene have been proposed as predisposing factors for myocardial infarction (MI) but published reports have given conflicting findings.

OBJECTIVE

The present study aimed to clarify the association between SNPs in PECAM-1 and MI using a meta-analysis of published studies.

METHODS

Medline, HuGE Navigator and SCOPUS Library databases were searched to identify case-control studies which examined the association of SNPs in PECAM-1 and MI. Data were extracted using standardized methods. Combined odds ratios (OR) with 95% confidence intervals (CI) for the association of SNPs with MI were calculated using a random effect approach and under additive, dominant and recessive models of inheritance.

RESULTS

A total of 7 studies comprising 3886 cases and 4097 controls fulfilled the inclusion criteria. Three SNPs in PECAM-1 were investigated, namely rs668 (Leu125Val), rs12953 (Ser563Asn) and rs1131012 (Arg670Gly). The GG genotype of rs1131012 was associated with a reduced risk of MI under a recessive (OR: 0.81; 95%CI: 0.69-0.94; p=0.010), but not additive and dominant models (p>0.05). This association was robust in sensitivity analyses and not subject to heterogeneity. No significant association was detected between rs668 and rs12953 with MI under any of the inheritance models.

CONCLUSION

The results of the current meta-analysis suggest that homozygous polymorphic genotype (GG) of the rs1131012 SNP may confer protection against MI. The impact of this variant on the expression and function of PECAM-1 needs to be elucidated in future investigations.

Inflammatory biomarkers for predicting cardiovascular disease

The pathology of cardiovascular disease (CVD) is complex; multiple biological pathways have been implicated, including, but not limited to, inflammation and oxidative stress. Biomarkers of inflammation and oxidative stress may serve to help identify patients at risk for CVD, to monitor the efficacy of treatments, and to develop new pharmacological tools. However, due to the complexities of CVD pathogenesis there is no single biomarker available to estimate absolute risk of future cardiovascular events. Furthermore, not all biomarkers are equal; the functions of many biomarkers overlap, some offer better prognostic information than others, and some are better suited to identify/predict the pathogenesis of particular cardiovascular events. The identification of the most appropriate set of biomarkers can provide a detailed picture of the specific nature of the cardiovascular event. The following review provides an overview of existing and emerging inflammatory biomarkers, pro-inflammatory cytokines, anti-inflammatory cytokines, chemokines, oxidative stress biomarkers, and antioxidant biomarkers. The functions of each biomarker are discussed, and prognostic data are provided where available.

CD31 exhibits multiple roles in regulating T lymphocyte trafficking in vivo

The role of CD31, an Ig-like molecule expressed by leukocytes and endothelial cells (ECs), in the regulation of T lymphocyte trafficking remains contentious. Using CD31-deficient mice, we show that CD31 regulates both constitutive and inflammation-induced T cell migration in vivo. Specifically, T cell:EC interactions mediated by CD31 molecules are required for efficient localization of naive T lymphocytes to secondary lymphoid tissue and constitutive recirculation of primed T cells to nonlymphoid tissues. In inflammatory conditions, T cell:EC CD31-mediated interactions facilitate T cell recruitment to Ag-rich sites. However, endothelial CD31 also provides a gate-keeping mechanism to limit the rate of Ag-driven T cell extravasation. This event contributes to the formation of Ag-specific effector T cell infiltrates and is induced by recognition of Ag on the endothelium. In this context, CD31 engagement is required for restoring endothelial continuity, which is temporarily lost upon MHC molecule ligation by migrating cognate T cells. We propose that integrated adhesive and signaling functions of CD31 molecules exert a complex regulation of T cell trafficking, a process that is differentially adapted depending on cell-specific expression, the presence of inflammatory conditions and the molecular mechanism facilitating T cell extravasation.

Primed T cell responses to chemokines are regulated by the immunoglobulin-like molecule CD31

CD31, an immunoglobulin-like molecule expressed by leukocytes and endothelial cells, is thought to contribute to the physiological regulation T cell homeostasis due to the presence of two immunotyrosine-based inhibitory motifs in its cytoplasmic tail. Indeed, loss of CD31 expression leads to uncontrolled T cell-mediated inflammation in a variety of experimental models of disease and certain CD31 polymorphisms correlate with increased disease severity in human graft-versus-host disease and atherosclerosis. The molecular mechanisms underlying CD31-mediated regulation of T cell responses have not yet been clarified. We here show that CD31-mediated signals attenuate T cell chemokinesis both in vitro and in vivo. This effect selectively affects activated/memory T lymphocytes, in which CD31 is clustered on the cell membrane where it segregates to the leading edge. We provide evidence that this molecular segregation, which does not occur in naïve T lymphocytes, might lead to cis-CD31 engagement on the same membrane and subsequent interference with the chemokine-induced PI3K/Akt signalling pathway. We propose that CD31-mediated modulation of memory T cell chemokinesis is a key mechanism by which this molecule contributes to the homeostatic regulation of effector T cell immunity.

Evaluation of PECAM-1 Gene Polymorphism in Patients with Periodontal Disease and Healthy Individuals

Objective. Our aim in this paper was to investigate the possible genetic association between three Ser563Asn, Leu125Val and Arg670Gly polymorphisms of the PECAM-1 gene and periodontitis. Methods. Genomic DNA was isolated from whole blood of 105 periodontal patient (52 with chronic periodontitis and 53 with aggressive periodontitis) and 101 healthy individuals. Samples were genotyped and analyzed for the three single-nucleotide polymorphisms (SNPs) of PECAM-1 using polymerase chain reaction with sequence-specific primers (PCR-SSPs). Results. A statistically significant difference was found between the genotypic distribution of the Ser563Asn polymorphism in patients with periodontitis compared to controls (P = 0.02). But there were no statistically significant difference between the allele frequencies in the different groups (P = 0.05). The other two polymorphisms did not show a statistically significant difference in their allele and genotype frequencies between the groups. There was no statistically significant difference found for any of the polymorphisms allele and genotype distribution in aggressive and chronic periodontitis either. Conclusions. No significant association was found between the polymorphism tested and the subgroups of periodontitis, further research is still necessary to determine whether this polymorphism can be used as a genetic marker of periodontitis.

Lessons from the endothelial junctional mechanosensory complex

Mechanotransduction plays a key role in both normal physiology and in diseases such as cancer, atherosclerosis and hypertension. Nowhere is this more evident than in the vascular system, where fluid shear stress from blood flow plays a critical role in shaping the blood vessels and in determining their function and dysfunction. Responses to flow are mediated in part by a complex of proteins comprised of PECAM-1, VE-cadherin and VEGFR2 at endothelial cell-cell junctions; all proteins that clearly have other, non-mechanical functions. We review recent progress toward understanding the functions and mechanisms of mechanotransduction by this complex and suggest some principles that may apply more broadly.

Minor histocompatibility antigens in Tunisians: could platelet endothelial cell adhesion molecule 1 marker be one of them?

Platelet endothelial cell adhesion molecule 1 (PECAM-1/CD31) is one of the human minor histocompatibility antigens that are the main targets of alloreactive T-cells after hematopoietic stem cells or solid organs transplantation. In order to investigate its polymorphism in Tunisians, three single nucleotide polymorphisms (SNPs) (rs668, rs12953 and rs1131012) were selected to perform an allele and haplotype analysis. Hundred-and-forty-two healthy and unrelated subjects were enrolled in this survey. Genomic DNAs were extracted using salting out method. SNP genotyping assays were performed with home-designed sequence-specific primers polymerase chain reaction (SSP-PCR). As a result, molecular analysis showed that PECAM-1 is one of the most polymorphic markers in the Tunisian population because minor allele frequency was 0.3, and minimum haplotype frequency was 0.03. A low linkage disequilibrium (D' = 0.45) between rs12953 and rs1131012 was noticed, although all other loci were in the Hardy-Weinberg equilibrium (minimum P value = 0.07). The frequencies were close to those reported in African-American and Caucasian groups.

Evidence for somatic gene conversion and deletion in bipolar disorder, Crohn's disease, coronary artery disease, hypertension, rheumatoid arthritis, type-1 diabetes, and type-2 diabetes

BACKGROUND

During gene conversion, genetic information is transferred unidirectionally between highly homologous but non-allelic regions of DNA. While germ-line gene conversion has been implicated in the pathogenesis of some diseases, somatic gene conversion has remained technically difficult to investigate on a large scale.

METHODS

A novel analysis technique is proposed for detecting the signature of somatic gene conversion from SNP microarray data. The Wellcome Trust Case Control Consortium has gathered SNP microarray data for two control populations and cohorts for bipolar disorder (BD), cardiovascular disease (CAD), Crohn's disease (CD), hypertension (HT), rheumatoid arthritis (RA), type-1 diabetes (T1D) and type-2 diabetes (T2D). Using the new analysis technique, the seven disease cohorts are analyzed to identify cohort-specific SNPs at which conversion is predicted. The quality of the predictions is assessed by identifying known disease associations for genes in the homologous duplicons, and comparing the frequency of such associations with background rates.

RESULTS

Of 28 disease/locus pairs meeting stringent conditions, 22 show various degrees of disease association, compared with only 8 of 70 in a mock study designed to measure the background association rate (P < 10-9). Additional candidate genes are identified using less stringent filtering conditions. In some cases, somatic deletions appear likely. RA has a distinctive pattern of events relative to other diseases. Similarities in patterns are apparent between BD and HT.

CONCLUSIONS

The associations derived represent the first evidence that somatic gene conversion could be a significant causative factor in each of the seven diseases. The specific genes provide potential insights about disease mechanisms, and are strong candidates for further study.

Strong association of the APOA5-1131T>C gene variant and early-onset acute myocardial infarction

BACKGROUND

Epidemiological studies support the role for a strong genetic component in the occurrence of early-onset myocardial infarction (MI), although the specific genetic variants responsible for familial clustering remain largely unknown.

METHODS

The Italian study of early-onset MI is a nationwide case-control study involving 1864 case patients <45 years old who were hospitalized for a first MI, and age/sex/place of origin-matched controls (n = 1864). We investigated the association between early-onset MI, lipid levels and 20 single nucleotide polymorphisms (SNPs) in the candidate genes ADIPOQ, APOA5, ALOX5AP, CYBA, IL6, LPL, PECAM1, PLA2G2A and PLA2G7, chosen because of previously reported associations with Coronary Heart Disease (CHD) or with CHD risk factors.

RESULTS

Of all the SNPs investigated, APOA5-1131T>C [(rs662799), minor allele frequency 0.084 (95% confidence interval (CI) 0.07-0.09)] alone showed a statistically significant association with risk of early-onset MI (p = 6.7 × 10(-5)), after Bonferroni correction, with a per C allele odds ratio of 1.44 (95% CI 1.23-1.69). In controls, APOA5-1131T>C was significantly associated with raised plasma triglyceride levels (p = 0.001), compared with non-carriers, the per C allele increase being 11.4% (95% CI 4-19%), equivalent to 0.15 mmol/L (95% CI 0.11-0.20 mmol/L). In cases, the association with early MI risk remained statistically significant after adjustment for triglycerides (p = 0.006).

CONCLUSIONS

The APOA5-1131C allele, associated with higher fasting triglyceride levels, strongly affects the risk for early-onset MI, even after adjusting for triglycerides. This raises the possibility that APOA5-1131T>C may affect the risk of early MI over and above effects mediated by triglycerides.

Association between platelet endothelial cellular adhesion molecule-1 polymorphisms and atherosclerosis: results of a study on patients from northern Italy

Adhesion of circulating cells to the arterial surface is among the first detectable events in atherogenesis. Cellular adhesion molecules, expressed by the vascular endothelium and by circulating leukocytes, mediate cell recruitment and their transendothelial migration. Platelet endothelial cellular adhesion molecule-1 (PECAM-1), involved in this migration, has been associated with the development of atherosclerosis. Studies have investigated an association between coronary artery disease (CAD) and single-nucleotide polymorphisms (SNPs) located in functionally important domains of the PECAM-1 gene with inconsistent results. Thus, we have analyzed the distribution of V125L, N563S, and G670R SNPs in patients and controls from northern Italy, and also analyzed another functional variant identified in the 5'-untranslated region (UTR) of the PECAM-1 gene (53 G-->A). The polymorphisms of PECAM-1 were genotyped by PCR amplification with sequence-specific primers (PCR-SSP) in 119 controls and 431 CAD patients. Our results demonstrate that genotype and allele frequencies for the 53 G/A polymorphism are significantly different in patients affected by CAD compared to healthy controls, whereas, as regards the V125L and N563S polymorphisms, only the allelic frequency is significantly different. We have shown that there were a significant differences for the 53 G/A and V125L and N563S polymorphisms of PECAM-1 in patients affected by CAD compared to controls. This demonstrates a possible involvement of this gene in contributing to the development of CAD. Therefore, an understanding of the role of the PECAM-1 molecule in this complex mechanism is of pivotal significance in further development of innovative and suitable medical therapies in the future.

Platelet-endothelial cell adhesion molecule-1 gene polymorphism and its soluble level are associated with ischemic stroke

Inflammation, characterized by the recruitment and adhesion of circulating leukocytes by cellular adhesion molecules, plays an important role in the pathogenesis of atherosclerosis. Genetic analyses of platelet-endothelial cell adhesion molecule-1 (PECAM-1), a key adhesion molecule in the progression of atherosclerosis, have provided conflicting results regarding the role of variation within the PECAM-1 gene and risk for coronary heart disease. No studies have examined the association of this polymorphism with ischemic stroke. Therefore, we investigated that PECAM-1 gene polymorphism and its soluble level are associated with ischemic stroke in Chinese population. We analyzed single-nucleotide polymorphisms of PECAM-1 gene Leu125Val, Asn563Ser, and Gly670Arg in 265 patients with ischemic stroke and 280 age- and sex-matched controls, using polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing method, while soluble PECAM-1 (sPECAM-1) levels were measured by enzyme-linked immunosorbent assay. There were significant differences in the genotype and allele frequencies of PECAM-1 gene Leu125Val polymorphism between the group of patients with ischemic stroke and the control group (p < 0.05). sPECAM-1 levels were increased in patients with ischemic stroke compared with controls (p < 0.01). Moreover, genotypes carrying the PECAM-1 125Val variant allele were associated with increased PECAM-1 levels compared to the homozygous wild-type genotype in patients with ischemic stroke. The Leu125Val polymorphism of PECAM-1 and its sPECAM-1 levels are associated with ischemic stroke in Chinese population. Our data suggest that the PECAM-1 gene may play a role in the development of ischemic stroke.

The PECAM-1 gene polymorphism — a genetic marker of myocardial infarction

We investigated a possible association between the C373G (Leu125Val) polymorphism in the platelet endothelial cell adhesion molecule-1 (PECAM-1) and myocardial infarction (MI) among patients with type 2 diabetes (T2DM) in the Slovene population (Caucasians). The study population of this cross-sectional analysis consisted of 452 subjects with T2DM lasting more than 10 years: 142 patients with MI (MI group) and 310 patients (control group) with no history of coronary diseases. There were significant differences of PECAM-1 genotype distribution in patients with MI (CC=28.2%, CG=47.2% and GG=24.6%) compared with subjects in the control group (CC=17.1%, CG=53.5% and GG=29.4%). The multivariate model showed that the CC genotype of the PECAM-1 gene polymorphism (C373G) (OR=1.9, 95% CI 1.2–3.0, P=0.007) was an independent risk factor for MI. The C allele frequency was also significantly higher (P=0.005) in MI (51.8%) than in control subjects (41%). In addition, our study revealed the connection between smoking habits, the duration of diabetes and the total and LDL cholesterol serum levels and MI in Slovene T2DM patients. We suggest that the tested polymorphism of PECAM-1 (C373G) is associated with MI. Therefore, it might be used as genetic marker of MI in T2DM.

Molecular genetics of myocardial infarction

Myocardial infarction (MI) is an important clinical problem because of its large contribution to mortality. The main causal and treatable risk factors for MI include hypertension, hypercholesterolemia or dyslipidemia, diabetes mellitus, and smoking. In addition to these risk factors, recent studies have shown the importance of genetic factors and interactions between multiple genes and environmental factors. Disease prevention is an important strategy for reducing the overall burden of MI, with the identification of markers for disease risk being key both for risk prediction and for potential intervention to lower the chance of future events. Although genetic linkage analyses of families and sib-pairs as well as candidate gene and genome-wide association studies have implicated several loci and candidate genes in predisposition to coronary heart disease (CHD) or MI, the genes that contribute to genetic susceptibility to these conditions remain to be identified definitively. In this review, we summarize both candidate loci for CHD or MI identified by linkage analyses and candidate genes examined by association studies. We also review in more detail studies that have revealed the association with MI or CHD of polymorphisms in MTHFR, LPL, and APOE by the candidate gene approach and those in LTA and at chromosomal region 9p21.3 by genome-wide scans. Such studies may provide insight into the function of implicated genes as well as into the role of genetic factors in the development of CHD and MI.

The proinflammatory phenotype of PECAM-1-deficient mice results in atherogenic diet-induced steatohepatitis

The severity of nonalcoholic steatohepatitis (NASH) is determined by environmental and genetic factors, the latter of which are incompletely characterized. Platelet endothelial cell adhesion molecule-1 (PECAM-1) is a 130-kDa transmembrane glycoprotein expressed on blood and vascular cells. In the present study, we provide data for the novel finding that genetic deficiency of PECAM-1 potentiates the development and progression of NASH. We found that the rate of development and severity of diet-induced NASH are markedly enhanced in PECAM-1-deficient [knockout (KO)] mice relative to wild-type (WT) mice, as measured by histological and biochemical evaluation. Livers from KO mice exhibited typical histological features of NASH, including macrovesicular fat accumulation, hepatocyte injury with infiltration of inflammatory cells, fibrosis, and heightened oxidative stress. Alanine aminotransferase, a marker for liver injury, was also significantly higher in KO compared with WT mice. Consistent with a role for PECAM-1 as a suppressor of proinflammatory cytokines, plasma levels of inflammatory cytokines, including TNF-alpha and monocyte chemoattractant protein-1 (MCP-1), were also significantly higher in KO compared with WT mice. These findings are the first to show that the PECAM-1-deficient mouse develops progressive nonalcoholic fatty liver disease (NAFLD), supporting a role for PECAM-1 as a negative regulator of NAFLD progression. Future examination of recently identified PECAM-1 allelic isoforms in humans as potential risk factors for developing NASH may be warranted.

PECAM-1: a multi-functional molecule in inflammation and vascular biology

Platelet endothelial cell adhesion molecule-1 (PECAM-1 or CD31) is a molecule expressed on all cells within the vascular compartment, being expressed to different degrees on most leukocyte sub-types, platelets, and on endothelial cells where its expression is largely concentrated at junctions between adjacent cells. As well as exhibiting adhesive properties, PECAM-1 is an efficient signaling molecule and is now known to have diverse roles in vascular biology including roles in angiogenesis, platelet function, and thrombosis, mechanosensing of endothelial cell response to fluid shear stress, and regulation of multiple stages of leukocyte migration through venular walls. This review will focus on some new developments with respect to the role of PECAM-1 in inflammation and vascular biology, highlighting the emerging complexities associated with the functions of this unique molecule.

PECAM-1/CD31 in Infarction and Longevity

Inflammation has recently proven to be associated with the pathogenesis of atherosclerosis and inflammatory genes are good candidates for the risk of developing atherosclerosis. The early phase of atherosclerosis involves the recruitment of inflammatory cells from the circulation and their transendothelial migration. This process is mainly mediated by cellular adhesion molecules, which are expressed by the vascular endothelium and by circulating leukocytes in response to several inflammatory stimuli. Adhesion of circulating cells to the arterial surface is among the first detectable events in atherogenesis. Cellular adhesion molecules, expressed by the vascular endothelium and by circulating leukocytes, mediate cell recruitment and their transendothelial migration. Platelet endothelial cellular adhesion molecule-1 (PECAM-1/CD31), involved in this migration, has been associated with the developmental course of atherosclerosis. Studies have investigated an association between coronary heart disease (CHD) and single nucleotide polymorphisms (SNP) located in functionally important domains of the PECAM-1/CD31 gene, with contrasting results. In particular, we previously analyzed for the following PECAM-1/CD31 SNP: Val125Leu, Asn563Ser, and Gly670Arg. The frequency of the Gly670Arg polymorphism was significantly higher in patients with myocardial infarction (MI), whereas the frequencies of the other two SNP (Leu125Val and Ser563Asn) were not significantly different between patients and controls. To check the validity of our results, we have analyzed the distribution of these SNP in centenarian men (age >99) from our homogeneous Sicilian population, since our previous studies have demonstrated that alleles associated with MI susceptibility are not included in the genetic background favoring longevity. We showed, as regard to polymorphisms of PECAM-1/CD31, that there were no significant differences between male patients affected by MI, male controls, and male centenarians. According to our hypothesis present results seemingly do not support a role for these SNP in conferring the susceptibility to MI at least in this Italian population.

Nested association between genetic variation in tryptophan hydroxylase II, bipolar affective disorder, and suicide attempts

BACKGROUND

Bipolar affective disorder (BPAD) is a common mental illness that is strongly associated with suicide. Suicidal behavior is thought to result from an interaction of genetic, neurobiological, and psychosocial factors and tends to cluster in families, suggesting specific familial factors distinct from those that underlie BPAD itself. Serotonin signaling has long been implicated in both BPAD and suicide, and the gene encoding the brain-expressed isoform of tryptophan hydroxlyase (TPH2) has been described. Markers in TPH2 have been implicated in suicide and major depressive disorder, but the results across studies are inconsistent. No studies have examined TPH2 in large samples of subjects with BPAD and suicide attempts (SA). We tested for a relationship between genetic variation in TPH2 and risk for BPAD and SA in a large family sample.

METHODS

The sample consisted of 2018 members of 670 families, ascertained through a sibling pair affected with bipolar I, bipolar II, or schizoaffective-bipolar disorder and diagnosed under DSM-III/IV criteria. Three single nucleotide polymorphisms representing the common haplotypes spanning TPH2 were analyzed.

RESULTS

Single-marker analysis failed to detect significant genetic association with BPAD or SA, but the number of informative families was small. Haplotype analysis showed significant association with both BPAD and SA, and the same haplotype was significantly associated with both BPAD and SA in a replication sample. Case-only analysis, stratified by SA, suggested that TPH2 was not an independent genetic risk factor for SA in this sample.

CONCLUSIONS

The TPH2 might contribute to the risk of both BPAD and SA in families with BPAD. Further studies are needed to uncover the functional genetic variation that accounts for the observed associations.

Candidate gene genotypes, along with conventional risk factor assessment, improve estimation of coronary heart disease risk in healthy UK men

BACKGROUND

One of the aims of cardiovascular genetics is to test the efficacy of the use of genetic information to predict cardiovascular risk. We therefore investigated whether inclusion of a set of common variants in candidate genes along with conventional risk factor (CRF) assessment enhanced coronary heart disease (CHD)-risk algorithms.

METHODS

We followed middle-aged men in the prospective Northwick Park Heart Study II (NPHSII) for 10.8 years and analyzed complete trait and genotype information available on 2057 men (183 CHD events).

RESULTS

Of the 12 genes previously associated with CHD risk, in stepwise multivariate risk analysis, uncoupling protein 2 (UCP2; P = 0.0001), apolipoprotein E (APOE; P = 0.0003), lipoprotein lipase (LPL; P = 0.007), and apolipoprotein AIV (APOA4; P = 0.04) remained in the model. Their combined area under the ROC curve (A(ROC)) was 0.62 (0.58-0.66) [12.6% detection rate for a 5% false positive rate (DR(5))]. The A(ROC) for the CRFs age, triglyceride, cholesterol, systolic blood pressure, and smoking was 0.66 (0.61-0.70) (DR(5) = 14.2%). Combining CRFs and genotypes significantly improved discrimination (P = 0.001). Inclusion of previously demonstrated interactions of smoking with LPL, interleukin-6 (IL6), and platelet/endothelial cell adhesion molecule (PECAM1) genotypes increased the A(ROC) to 0.72 (0.68-0.76) for a DR(5) of 19.1% (P = 0.01 vs CRF combined with genotypes).

CONCLUSIONS

For a modest panel of selected genotypes, CHD-risk estimates incorporating CRFs and genotype-risk factor interactions were more effective than risk estimates that used CRFs alone.

The alleles of PECAM-1

Previous studies have reported the existence of eleven different single nucleotide polymorphisms (SNPs) within human PECAM-1 mRNA, several of which have recently been associated with disease. Though SNPs in the PECAM-1 gene have been known for some time, the genetic background on which they exist, and their association into distinct allelic isoforms has not yet been established. To identify the major allelic isoforms of PECAM-1, we determined the nucleotide sequence of individual full-length cloned cDNAs derived from anonymous, unrelated volunteer individuals. Initial sequence analysis of 34 alleles from 17 individuals confirmed the presence of two distinct human PECAM-1 alleles (L(98)S(536)R(643) and V(98)N(536)G(643)) within the human population. Each of these were found, upon more detailed analysis, to be superimposed on a previously unreported a2479g nucleotide polymorphism within the 3' untranslated region (3'UTR) that occurred on both allelic isoforms - yielding a total of four major alleles. Multiplex Luminex bead analysis of an additional 259 individuals allowed identification of 117 individuals homozygous for either the L(98)S(536) or V(98)N(536) allele, and sequence analysis around the R643G and a2479g polymorphic sites permitted accurate determination of significant differences in the gene frequencies of LSRa, LSRg, VNGa, and VNGg among Caucasian individuals. Identification of these PECAM-1 allelic isoforms should facilitate future detailed examination of PECAM-1-related disease associations, and may help resolve previously disparate results.

Investigating the Genetic Determinants of Cardiovascular Disease Using Candidate Genes and Meta-analysis of Association Studies

Coronary artery disease (CAD) has a polygenic basis, and identification of CAD susceptibility genes has the potential to aid the development of new treatments and enhance prediction of disease risk. Thus far, the strategy has firstly been to choose "candidate" genes coding for important "rate-limiting" proteins in the homeostatic systems involved in maintaining cardiovascular health; secondly to identify common variants in these candidate genes; thirdly to carry out genotyping and statistical analysis using genetic association studies; and finally to test the functional effects of the identified variants in vitro and in vivo. However, lack of reproducibility of genetic association studies has led to uncertainty about the nature and number of genes involved. In part this is because many of the studies conducted have not been adequately powered to detect small risk effects, or to permit adequate exploration of gene-gene or gene-environment interactions in a robust manner. Spurious positive and negative associations due to type I and type II statistical errors are likely to co-exist with real associations in the published literature. By utilising all available data to increase statistical power, meta-analysis of genetic association studies is increasingly being used to identify genotypic risk with a greater degree of precision. Though potentially powerful, this approach may be prone to publication bias. Therefore, very large genetic association studies will also be required to identify risk genes for CAD. This review lays out the framework for the candidate gene approach for CAD and illustrates this with published results from a UK prospective study of 3000 middle-aged men.