ICAM1 Polymorphisms Research Articles

Prediction value of intercellular adhesion molecule-1 gene polymorphisms for epithelial ovarian cancer risk, clinical features, and prognosis

Intercellular adhesion molecule-1 (ICAM-1, encoded by ICAM-1) is implicated in tumorigenesis and tumor progression. ICAM-1 modulates the susceptibility to several types of cancer and the disease prognosis; however, its role in epithelial ovarian cancer (EOC) is unclear. Here, we evaluate single nucleotide polymorphisms (SNPs) in ICAM-1 as predictors of EOC risk and prognosis. Six ICAM-1 polymorphisms were genotyped in 408 patients with EOC and 520 controls using the MassARRAY system. The ICAM-1 mRNA levels in 89 EOC tissues and 35 normal ovarian tissues were examined using quantitative PCR. The ICAM-1 rs5498 G allele was associated with increased tumor grade (OR=2.650) and EOC risk (OR=1.405). This risk was more evident in females who had first-degree relatives (FDRs) with a tumor (OR=3.475) or who experienced early menarche (OR=2.774). The ICAM-1 expression in the cancerous tissue was elevated compared with that of normal ovarian tissues (p<0.0001), and it was associated with an rs5498 genotype (p=0.0002). ICAM-1 SNPs did not significantly predict the overall EOC survival (p>0.05). However, the rs5498 G allele correlated with EOC survival time in patients whose FDRs suffered from a tumor (p=0.001). ICAM-1 rs5498 likely confers a high risk for EOC in G allele carriers accompanied by up-regulation of ICAM-1 expression during carcinogenesis. The combination of ICAM-1 rs5498 and tumor history predicts the EOC prognosis.

The Impact of ICAM1 and VCAM1 Gene Polymorphisms on Chronic Allograft Nephropathy and Transplanted Kidney Function

ICAM-1 and VCAM-1 adhesion molecules play important roles in the immune response and emergence of chronic allograft nephropathy (CAN). The several polymorphisms of ICAM1 and VCAM1 genes are associated with changes in molecular expression therefore affecting allograft function and immune responses after kidney transplantation. The aim of this study was to examine the impact of polymorphisms in ICAM1 and VCAM1 genes on biopsy-proven CAN and renal allograft function. The 270 Caucasian renal transplant recipients (166 men and 104 women) were genotyped for the rs5498 ICAM1 and rs1041163 and rs3170794 VCAM1 gene polymorphisms using real-time polymerase chain reaction. There was no correlation between polymorphisms and CAN. Creatinine concentrations in the first month after transplantation differed between the rs5498 ICAM1 genotypes (P = .095), being higher for GG carriers (AA + AG vs GG, P =.07) albeit not with statistical significance. Creatinine concentrations at 12, 24, and 36 months after transplantation differed significantly among rs5498 ICAM1 genotypes (P = .0046, P =.016, and P = .02) and were higher among GG carriers (AA + AG vs GG, P = .001, P = .004, and P = .006). Rs5498 ICAM1 GG genotype and receipient male gender were independent factors associated with higher creatinine concentrations. These results suggest that the rs5498 ICAM1 GG genotype may be associated with long-term allograft function.

The impact of ICAM1 and VCAM1 gene polymorphisms on long-term renal transplant function and recipient outcomes

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are implicated in endothelial cell-leukocyte adhesion. Several functional polymorphisms that affect the expression of ICAM-1 and VCAM-1, and therefore post-transplant immunological response, have been found in genes of these molecules. The aim of this study was to examine the impact of ICAM1 and VCAM1 gene polymorphisms on long-term renal transplant function and recipient outcome during a 5-year follow-up period. The study enrolled 269 Caucasian renal transplant recipients (165 males, 104 females, mean age 47.58 ± 12.96 years) remaining under observation for 5 years. Genotyping of the c.1405A>G (Lys469Glu, rs5498) ICAM1, T(-1592)C (rs1041163), and T(-833)C (rs3170794) VCAM1 genes polymorphisms was performed using real-time PCR. The rs5498 ICAM1 GG genotype was an independent risk factor associated with increased creatinine concentration at 12, 24, 36, 48, and 60 months after transplantation (p=0.0004, p=0.02, p=0.01, p=0.01 and p=0.04, respectively). Creatinine concentrations 36 and 48 months after transplantation were higher among CC homozygotes of the rs1041163 VCAM1 (TT+CT vs. CC, p=0.049 and p=0.04, respectively). The C allele of the rs1041163 VCAM1 gene polymorphism was identified as a risk factor for dialysis after transplantation (HR=3.323, 95%CI=1.44-7.67, p=0.005). The C allele of the rs1041163 VCAM1 gene was at the border of statistical significance as a risk factor for death after transplantation (p=0.06). These results suggest that the rs5498 ICAM1 GG genotype is correlated with early and long-term allograft failure. The C allele of the rs1041163 VCAM1 gene may be associated with long-term allograft failure and graft loss, as well as increased morbidity after transplantation.

Effect of the ICAM1 and VCAM1 Gene Polymorphisms on the Renal Transplant Outcome - the Follow-Up Study

Effect of the ICAM1 and VCAM1 Gene Polymorphisms on the Renal Transplant Outcome - the Follow-Up Study

Correlation between ICAM1 and VCAM1 gene polymorphisms and histopathological changes in kidney allograft biopsies

IntroductionThe immunoglobulin-like molecules intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1) are responsible for endothelial cell-leukocyte adhesion followed by transmigration of leukocytes through the endothelial cell lining. The aim of this study was to examine the correlation between polymorphisms in ICAM1 and VCAM1 genes and histopathological changes in transplanted kidney biopsies.Material and methodsThe study enrolled 82 Caucasian renal transplant recipients (48 males, 34 females). Genotyping of the rs5498 ICAM1 and the rs1041163 and rs3170794 VCAM1 gene polymorphisms was performed using real-time polymerase chain reaction (PCR). Biopsies were performed in 82 patients and were reviewed by a renal pathologist and the Banff working classification criteria were used.ResultsThere were no significant associations between VCAM gene polymorphisms and histopathological changes in kidney allograft biopsies. ICAM1 gene polymorphism was associated with the grade of interstitial fibrosis. Interstitial fibrosis was more severe among individuals with the G allele than those with the A allele (AA vs. GG+AG, p = 0.017). There were no statistically significant associations between ICAM1 gene polymorphism and other histopathological changes in kidney allograft biopsies.ConclusionsThe results of our study suggest that rs5498 ICAM1 gene polymorphism is associated with the grade of interstitial fibrosis in kidney recipients and the changes are more severe in patients with the G allele.

G/R 241 Polymorphism of Intercellular Adhesion Molecule 1 (ICAM-1) Is Associated with Fuchs Uveitis

To investigate potential associations of the ICAM-1 gene polymorphisms and Fuchs uveitis in a cohort of Italian patients. Seventy-one consecutive Italian patients affected by Fuchs uveitis were observed at the Ocular Immunology Unit, Arcispedale S. Maria Nuova (Reggio Emilia, Italy) from 2002 to 2008. Two hundred twenty-six healthy Italian blood donors from the same geographic area were selected as the control group. All Fuchs uveitis patients and control subjects were genotyped by polymerase chain reaction (PCR) and allele-specific oligonucleotide techniques for ICAM-1 polymorphisms at codon 241 (exon 4). The frequency of the ICAM-1 G/R 241 polymorphism was significantly higher in Fuchs uveitis than in the control subjects (16.9% vs. 5.8%; P=0.006, Pcorr=0.012; odds ratio, 3.3; 95% confidence interval, 1.4-7.7). No significant association between clinical features and ICAM-1 polymorphisms was found. This study demonstrates for the first time that the ICAM-1 G/R 241 polymorphism may represent a candidate gene for Fuchs uveitis susceptibility.

9052 Single-nucleotide polymorphism K469E G>A in ICAM-1 gene in non-small cell lung cancer

Inflammation plays an important role in promoting ovarian tumorigenesis and cancer progression. However, the relationship between polymorphisms in inflammatory response genes and risk of ovarian cancer remains poorly understood. In this study, we investigated the association of PPARG Pro12Ala, IL6-174G/C, E-selectin S128R, NFKB1-94 ins/del, NFKBIA-826C/T, and ICAM-1 K469E polymorphisms with ovarian cancer risk in a Chinese population.Genotyping of the polymorphisms was performed on 687 cases and 687 controls employing the PCR-RFLP technique, and the logistic regression model was used to measure the risk association.A significantly increased risk association was observed for the heterozygous genotypes of PPARG [odds ratio (OR) = 1.52, 95% confidence interval (CI) = 1.01–2.29] and E-selectin (OR = 1.77, 95% CI = 1.07–2.93) polymorphisms, as well as the homozygous ins/ins genotype of NFKB1 polymorphism (OR = 1.39, 95% CI = 1.00–1.92). By contrast, ICAM-1 KE genotype was associated with a decreased ovarian cancer risk (OR = 0.77, 95% CI = 0.60–0.98). In addition, the NFKB1 del/del + NFKBIA TT combination was also found to be associated with a decreased ovarian cancer risk, with OR = 0.12 (95% CI = 0.01–0.95). The associations of the NFKB1 and ICAM-1 polymorphisms replicated the findings of previous reports, assuring the reliability of the results obtained.NFKB1 and ICAM-1 polymorphisms could serve as useful ovarian cancer risk prediction biomarkers for the Chinese population, while the utility of PPARG and E-selectin polymorphisms as biomarkers requires further confirmation in independent ovarian cancer cohorts.

A Systematic Meta-Analysis of Genetic Association Studies for Diabetic Retinopathy

OBJECTIVEDiabetic retinopathy is a sight-threatening microvascular complication of diabetes with a complex multifactorial pathogenesis. A systematic meta-analysis was undertaken to collectively assess genetic studies and determine which previously investigated polymorphisms are associated with diabetic retinopathy.RESEARCH DESIGN AND METHODSAll studies investigating the association of genetic variants with the development of diabetic retinopathy were identified in PubMed and ISI Web of Knowledge. Crude odds ratios (ORs) and 95% CIs were calculated for single nucleotide polymorphisms and microsatellite markers previously investigated in at least two published studies.RESULTSTwenty genes and 34 variants have previously been studied in multiple cohorts. The aldose reductase (AKR1B1) gene was found to have the largest number of polymorphisms significantly associated with diabetic retinopathy. The z−2 micro satellite was found to confer risk (OR 2.33 [95% CI 1.49–3.64], P = 2 × 10−4) in type 1 and type 2 diabetes and z+2 to confer protection (0.58 [0.36–0.93], P = 0.02) against diabetic retinopathy in type 2 diabetes regardless of ethnicity. The T allele of the AKR1B1 promoter rs759853 variant is also significantly protective against diabetic retinopathy in type 1 diabetes (0.5 [0.35–0.71], P = 1.00 × 10−4), regardless of ethnicity. These associations were also found in the white population alone (P < 0.05). Polymorphisms in NOS3, VEGF, ITGA2, and ICAM1 are also associated with diabetic retinopathy after meta-analysis.CONCLUSIONSVariations within the AKR1B1 gene are highly significantly associated with diabetic retinopathy development irrespective of ethnicity. Identification of genetic risk factors in diabetic retinopathy will assist in further understanding of this complex and debilitating diabetes complication.

The Genetics of Cervical Artery Dissection

The pathophysiology of cervical artery dissections (CAD), a major cause of ischemic stroke in young adults, is poorly understood. Several arguments suggest a genetic predisposition. We systematically reviewed all published data on genetic risk factors for CAD and performed a meta-analysis of association studies with the MTHFR C677T polymorphism. Rarely, CAD is associated with a known monogenic connective tissue disease, mainly vascular Ehlers-Danlos syndrome. However, in the large majority of CAD cases, there is no evidence for a known monogenic disease. Several arguments, including the association of CAD with dermal connective tissue abnormalities that are inherited, suggest that genetic factors also play a role in "sporadic" CAD as part of a multifactorial predisposition. We identified 15 genetic association studies: 10 were negative and 5 reported associations of 3 genetic variants in 3 different candidate genes. Two studies reported associations with polymorphisms in ICAM-1 and COL3A1, but neither has been replicated. Three studies reported an association with the MTHFR 677TT genotype, but 3 other studies did not replicate this. A meta-analysis of these data identified an overall significant association of the MTHFR 677TT genotype with CAD (OR, 1.67; 95% CI, 1.21 to 2.31). We also identified 9 studies screening candidate genes for mutations and 4 linkage studies, yielding mostly negative results. Although several interesting hypotheses were generated, the majority of genetic studies in CAD have been negative until now, but they were markedly underpowered. Progress in unraveling the genetics of CAD will require the collection of DNA samples from large multicenter series.

Expression of ICAM1 and VCAM1 serum levels in rheumatoid arthritis clinical activity. Association with genetic polymorphisms.

To investigate the association of sICAM-1 and sVCAM-1 with ICAM1 721G>A and VCAM1 1238G>C polymorphisms and rheumatoid arthritis (RA) clinical activity, sixty RA patients and 60 healthy non-related subjects (HS) matched for age and sex were recruited. Soluble adhesion molecules were determined by ELISA technique. Rheumatoid factor (RF), C reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) were measured by routine methods. Disability and clinical activity was measured with Spanish-HAQ-DI and DAS28 scores, respectively. The ICAM1 and VCAM1 polymorphism were identified using the PCR-RFLP procedure. Inter-group comparison showed increased levels of sICAM-1 and sVCAM-1 in RA patients (284 and 481 ng/mL) versus HS (132 and 280 ng/mL); in the RA group, significant correlations between sVCAM-1 and RF (r = 0.402), ESR (r = 0.426), Spanish-HAQ-DI (r = 0.276), and DAS28 (r = 0.342) were found, whereas sICAM-1 only correlated with RF (r = 0.445). In RA patients, a significant association with the 721A allele of ICAM1 polymorphism (p = 0.04), was found. In addition, the allele impact (G/A + A/A) of this polymorphism was confirmed, (p = 0.038, OR = 2.3, C.I. 1.1–5.0). sVCAM-1 and sICAM-1 serum levels reflected the clinical status in RA, independently of the ICAM1 and VCAM1 polymorphism. However, the ICAM1 721A allele could be a genetic marker to RA susceptibility.

Expression of ICAM1 and VCAM1 Serum Levels in Rheumatoid Arthritis Clinical Activity. Association with Genetic Polymorphisms

To investigate the association of sICAM-1 and sVCAM-1 with ICAM1 721G&gt;A and VCAM1 1238G&gt;C polymorphisms and rheumatoid arthritis (RA) clinical activity, sixty RA patients and 60 healthy non-related subjects (HS) matched for age and sex were recruited. Soluble adhesion molecules were determined by ELISA technique. Rheumatoid factor (RF), C reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) were measured by routine methods. Disability and clinical activity was measured with Spanish-HAQ-DI and DAS28 scores, respectively. The ICAM1 and VCAM1 polymorphism were identified using the PCR-RFLP procedure. Inter-group comparison showed increased levels of sICAM-1 and sVCAM-1 in RA patients (284 and 481 ng/mL) versus HS (132 and 280 ng/mL); in the RA group, significant correlations between sVCAM-1 and RF (r= 0.402), ESR (r= 0.426), Spanish-HAQ-DI (r= 0.276), and DAS28 (r= 0.342) were found, whereas sICAM-1 only correlated with RF (r= 0.445). In RA patients, a significant association with the 721A allele of ICAM1 polymorphism (p= 0.04), was found. In addition, the allele impact (G/A+A/A) of this polymorphism was confirmed, (p= 0.038, OR = 2.3, C.I. 1.1–5.0). sVCAM-1 and sICAM-1 serum levels reflected the clinical status in RA, independently of the ICAM1 and VCAM1 polymorphism. However, the ICAM1 721A allele could be a genetic marker to RA susceptibility.

Interactions between rs5498 polymorphism in the ICAM1 gene and traditional risk factors influence susceptibility to coronary artery disease

Coronary artery disease (CAD) depends on multiple genetic and environmental factors. Adhesion molecules are markers of endothelium dysfunction. Intercellular adhesion molecule-1 (ICAM-1) interacts with leukocyte integrins and promotes atherosclerotic process at the surface of endothelial cells. The aim of the study was to assess the association between ICAM1 rs5498 polymorphism and CAD and to establish whether there are any interactions between this polymorphism and traditional risk factors in determining the risk of CAD. We studied 191 cases with angiographically documented CAD and 203 controls with no signs of cardiovascular diseases. The ICAM1 polymorphism was genotyped using PCR-RFLP method. Data were analyzed with the STATISTICA 7.1 and EpiInfo 6 softwares. We did not observe significant differences in the distribution of genotypes and alleles of rs5498 between cases and controls. We only found a tendency to a higher prevalence of G allele carriers (AG + GG) in patients compared to controls (68 vs. 64%, P = 0.399). A synergistic effect of G allele carrier-state and smoking that had influenced the risk of CAD [synergy index multiplicative (SIM = 2.09)] was observed. Smoking carriers of G allele compared to non-smoking AA were more prevalent in CAD group (39.8%) than among controls (13.3%, P < 0.0001, OR 4.81). Moreover, there was also a synergistic effect between G allele carrier-state and an elevated level of triacylglycerols (TG) (SIM = 1.28) increasing the risk of CAD. There is a synergistic interaction between rs5498 genotype and smoking that increases the risk of CAD.

Circulating secretory type IIA phospholipase A2, lipoprotein (a) and soluble cellular adhesion molecule levels in patients with angina pectoris

Objectives To examine the plasma levels of secretory type IIA phospholipase A2 (sPLA 2-IIA), lipoprotein (a) [Lp(a)], soluble intercellular adhesion molecule-1 (sICAM-1) and soluble platelet endothelial CAM-1 (sPECAM-1), as well as ICAM-1 (K469E) and PECAM-1 (Leu125Val) gene polymorphisms, in patients with unstable angina pectoris (UAP) and stable AP (SAP). Design and methods We enrolled 75 patients with SAP, 72 with UAP and 80 controls without angina. Blood samples were obtained before angiography. Results The concentrations of sPLA 2-IIA, sICAM-1 and sPECAM-1 were higher for UAP patients than for SAP patients and controls, and the level of Lp(a) was higher for UAP patients than for controls. Lp(a) and sPLA 2-IIA levels were significantly correlated, and high plasma Lp(a) level (≥ 300 mg/L) was an independent risk factor for angina. Conclusion Lp(a) may play an important role in the development of angina. Further research should investigate the role of sPLA 2-IIA, sICAM-1 and sPECAM-1 in UAP.

ICAM1 R241 is not associated with celiac disease in the Spanish population

Celiac disease (CD) is a chronic intestinal inflammatory disease that develops in genetically susceptible individuals after gluten ingestion. The ICAM1 gene, located in the CD linkage region 19p13, encodes an intercellular adhesion molecule (ICAM-1) involved in inflammatory processes. Increased levels of ICAM-1 were observed in intestinal biopsies and in sera of CD patients. In addition, an association between the ICAM1 polymorphism G241R and CD patients has been recently described in a French population. Our aim in this study was to analyze the role of ICAM1 polymorphisms in CD susceptibility in the Spanish population. We performed a case-control study with 608 CD patients and 537 healthy control individuals and a family study including 231 trios. Four ICAM1 single nucleotide polymorphisms (SNPs) were analyzed: three nonsynonymous, R478W (rs5030400), P352L (rs1801714) and G241R (rs1799969); and one intronic, rs281432. Despite having above 98% statistical power to detect the association described in the French population (odds ratio = 1.7), we did not find any differences in genotypic or allelic frequencies of the G241R polymorphism between our CD patients and controls, and no differences were observed when the other SNPs were analyzed. Therefore, in our population our results discard the important previously described role of ICAM1 G241R in celiac disease.

ICAM-1, GRP-78, and NFkB gene polymorphisms and clinical outcome in patients (pts) with metastatic colorectal cancer (mCRC) treated with first line 5-FU or capecitabine in combination with oxaliplatin and bevacizumab (FOLFOX/BV or XELOX/BV)

4134 Background: We evaluated polymorphisms of genes involved in angiogenesis, cell proliferation, and cell-cell or cell-matrix adhesion as potential predictors of clinical outcome in pts with mCRC...

ICAM1 and VCAM1 polymorphisms, coronary artery calcium, and circulating levels of soluble ICAM-1: The multi-ethnic study of atherosclerosis (MESA)

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) may be important contributors to the development and progression of atherosclerosis. Using a stratified random sample of 2880 participants of the Multi-Ethnic Study of Atherosclerosis we investigated the relationship of 12 ICAM1 and 17 VCAM1 SNPs and coronary artery calcium (CAC) and ICAM1 SNPs and circulating levels of soluble ICAM-1 (sICAM-1). There were no ICAM1 or VCAM1 SNPs significantly associated with CAC in any of the four race/ethnic groups. In a subset of 1451 subjects with sICAM-1 measurements, we observed a significant association with rs5491 in all four race/ethnic groups corroborating previous research that has shown that the T-allele of rs5491 interferes with the monoclonal antibody used to measure sICAM-1 in this study. After excluding all rs5491 T-allele carriers, several ICAM1 SNPs were significantly associated with sICAM-1 levels; rs5496 in African Americans, rs5498 and rs3093030 in European Americans, and rs1799969 in Hispanics. Our results identified ICAM1 polymorphisms that were significantly associated with sICAM-1 level but not CAC, a subclinical marker of atherosclerosis.

Expression of endothelial intercellular adhesion molecule-1 is determined by genotype: Effects on efficiency of leukocyte adhesion to human endothelial cells

Two biallelic polymorphisms, previously described in the human intercellular adhesion molecule (ICAM)-1 gene at codon 241 (glycine [G] to arginine [R] substitution) and codon 469 (glutamic acid [E] to lysine [K] substitution) have been associated with a number of diseases including myocardial infarction, transplant rejection, and diabetes. However, the functional significance of these polymorphisms has not been determined. ICAM-1 cell surface expression and ICAM-1-mediated leukocyte adhesion were investigated using Cos7 transfected with ICAM-1 polymorphic variants or human umbilical vein endothelial cells (HUVEC) of different ICAM-1 genotypes. There was significantly higher expression of surface ICAM-1 on Cos7 transfected with a plasmid encoding the GE (G241/E469) ICAM-1 variant or untreated HUVEC of GEGE (G241/E469 homozygous genotype). ICAM-1-mediated adhesion of peripheral blood mononuclear cells (PBMC) to GE-Cos7 cells or TNF-treated GEGE HUVEC was significantly increased. However, there was no significant difference in adhesion of PBMC to recombinant ICAM-1 of each polymorphic variant plated onto plastic wells. We conclude that the GE genotype of ICAM-1 is associated with greater cell surface expression of ICAM-1, which in turn leads to greater adhesion of leukocytes. This may explain the previously described associations of ICAM-1 polymorphisms with chronic inflammatory disease.

ICAM-1 polymorphisms (G241R, K469E), in coronary artery disease and myocardial infarction.

Inflammation plays a critical role in atherogenesis. The initial step in atherosclerosis is the adhesion of leukocytes to activated endothelial cells mediated by ICAM-1, an inflammatory protein. Several polymorphisms for Intracellular adhesion molecule -1(ICAM-) gene have been described. To determine the possible role of G241R and K469E polymorphisms in development of coronary artery disease and MI. G241R polymorphism was investigated in 303 patients with angiographically documented CAD, including 151 patients with acute or chronic myocardial infarction (MI), and a control group consisting of 141 healthy subjects with normal coronary angiogram. K469E polymorphism was investigated in 309 patients with CHD, including155 patients with MI, and compared with 150 healthy subjects without CHD as the control group. Finally, G241R and K469R polymorphisms were assessed concurrently in 300 patients with CHD including 152 patients with MI and 140 healthy normal subjects without coronary heart disease (CHD). Although the frequency of GR and RR genotypes were higher in the control group compared to the CHD patients, the difference was not statistically significant (7.09% vs. 5.6% and 1.4% vs. 0%, P=0.27and P=0.24, respectively). Despite the higher frequency of KK genotype in the CHD group, the difference was not significant (29.1% vs. 24.6%, P=0.62). KKGG genotype was more frequent in the CHD group, however the difference was not significant (31.1% vs. 27.3%, P=0.66). No strong relation was found between G241R and K469E polymorphisms and occurrence of CHD and MI in the studied population from Fars province, Iran.

A model of the complex between the PfEMP1 malaria protein and the human ICAM-1 receptor

Malaria is caused by protozoan parasites of the genus Plasmodium. Four species of Plasmodium can infect humans: P. falciparum, P. malariae, P. vivax, and P. ovale. P. falciparum is the only able to cytoadhere to the surface of postcapillary endothelial cells. A key role in cytoadherence is played by the interaction between the PfEMP1 P. falciparum protein and the human intracellular adhesion molecule (ICAM-1) although very little is known about the molecular details of this complex. Here we propose a model for this interaction on the basis of a homology model of the functional domain of PfEMP1 and of the ICAM-1 three dimensional structures. Our model is consistent with the results of many experimental observations, provides a rational explanation for the different binding abilities of different strains of P. falciparum and explains the reduced binding affinity of the A4 strain of P. falciparum for the ICAM-1(Kilifi) polymorphism. On the basis of our model, we can also explain why the murine ICAM-1, although sharing 70% sequence similarity with its human homologue, does not bind PfEMP1, and why the binding of fibrinogen and PfEMP1 to ICAM-1 is mutually exclusive. The model of the complex proposed here can serve as a useful tool for the design and interpretation of biochemical and immunological experimental results.

Haplotype-based association analysis of 56 functional candidate genes in the IBD6 locus on chromosome 19

Evidence from four independent linkage studies and two meta-analyses of genome-wide data support the existence of a locus conferring susceptibility to inflammatory bowel diseases (IBD) in chromosomal region 19p. Identification of a susceptibility allele in this approximately 28.5 Mb region with over 600 genes is a formidable task. To tackle this problem, we undertook two approaches: (1) haplotype-based candidate-gene screen, and (2) evaluation of previously reported associations. For the former, we selected genes with potential implication in IBD pathogenesis based on published functional and expression data, typed SNPs, constructed haplotypes, screened for association in 180 IBD trios, and followed up preliminary associations in 343 IBD patients and 207 control individuals. Overall, we analyzed 465 SNPs, and 260 haplotypes distributed across 56 candidate genes. We found suggestive evidence of association (nominal P<0.01) with four genes (C3, FCER2, IL12RB1, and CRLF1) in a screening stage, but were unable to confirm these preliminary observations at follow-up. In the second approach, we typed four nonsynonymous polymorphisms in genes C3 (R102G and L314P) and ICAM1 (G241R and K469E) in four independent cohorts totaling 2178 IBD cases. We evaluated these data together with previously published reports for three of these variants (C3-Gly102, ICAM1-Arg241, and ICAM1-Glu469), in a meta-analysis. Our pooled meta-analysis provides compelling evidence against association of these variants with disease. Overall, we performed the most comprehensive candidate-gene association study for IBD to date. The information hereby generated constitutes a valuable resource to investigate other common genetic immune diseases, such as celiac disease.