Intercellular adhesion molecule-1 polymorphisms in Korean patients with rheumatoid arthritis

Analysis of the Whole-Genome Sequences from an Equus Parent-Offspring Trio Provides Insight into the Genomic Incompatibilities in the Hybrid Mule

Interspecific hybridization often shows negative effects on hybrids. However, only a few multicellular species, limited to a handful of plants and animals, have shown partial genetic mechanisms by which hybridization leads to low fitness in hybrids. Here, to explore the outcome of combining the two genomes of a horse and donkey, we analyzed the whole-genome sequences from an Equus parent-offspring trio using Illumina platforms. We generated 41.39× and 46.21× coverage sequences for the horse and mule, respectively. For the donkey, a 40.38× coverage sequence was generated and stored in our laboratory. Approximately 24.86 million alleles were discovered that varied from the reference genome. Single nucleotide polymorphisms were used as polymorphic markers for assigning alleles to their parental genomic inheritance. We identified 25,703 Mendelian inheritance error single nucleotide polymorphisms in the mule genome that were not inherited from the parents through Mendelian inheritance. A total of 555 de novo single nucleotide polymorphisms were also identified. The rate of de novo single nucleotide polymorphisms was 2.21 × 10^-7 in the mule from the Equus parent-offspring trio. This rate is obviously higher than the natural mutation rate for Equus, which is also consistent with the previous hypothesis that interracial crosses may have a high mutation rate. The genes associated with these single nucleotide polymorphisms are mainly involved in immune processes, DNA repair, and cancer processes. The results of the analysis of three genomes from an Equus parent-offspring trio improved our knowledge of the consequences of the integration of parental genomes in mules.

Analysis of ICAM1 gene polymorphism in Slovak multiple sclerosis patients

Infiltration of immune cells into CNS is one of the essential events in multiple sclerosis (MS) development. Adhesion molecules like the intercellular adhesion molecule 1 (ICAM-1) play critical role in this process. Therefore, the ICAM1 gene containing two important single-nucleotide polymorphisms (SNPs) belongs to candidate loci with possible involvement in MS susceptibility and/or severity. The objective of our case-control study was to analyze the association of two functional ICAM1 polymorphisms rs1799969 (or G241R) and rs5498 (or K469E) with susceptibility to MS and evaluate their influence on the age at disease onset, severity, neurological disability and progression rate. Two hundred forty-eight MS subjects (mean 39.2 years) and 208 age-matched controls (mean 35.6 years) were involved in the study. Genotyping of ICAM1 rs1799969 and rs5498 SNPs was performed by PCR-RFLP. Presence of the rs3135388 polymorphism tagging the major MS risk allele HLA-DRB1*15:01 allele was determined as well. Our analysis revealed no statistically significant association of ICAM1 polymorphisms with risk of MS development in the Slovak population. Stratification of study cohorts by gender, age at onset and presence of the HLA-DRB1*15:01 risk allele showed only moderate changes. Correlation of clinical findings as age at onset, Kurtzke Expanded Disability Status Scale, Multiple Sclerosis Severity Score and progression index with ICAM1 genotypes in MS patients revealed no significant association; however, patients with earlier onset of MS showed slightly higher frequencies of the homozygous G allele at rs5498 in comparison to other genotypes (P = 0.04), suggesting that GG carriers tend to induce MS at an earlier age.

Investigation of ICAM-1 and β3 integrin gene variations in patients with brain tumors

BACKGROUND

Primary brain tumors constitute a small percent of all malignant cancers, but their etiology remains poorly understood. β3 integrin (ITGB3) has been recognized to play influential roles in angiogenesis, tumor growth and metastasis. Intercellular adhesion molecule-1 (ICAM-1) is a surface glycoprotein important for tumor invasion and angiogenesis. The aim of this study was to investigate whether specific genetic polymorphisms of ICAM-1 and ITGB3 could be associated with brain cancer development and progression in a Turkish population. Our study is the first to our knowledge to investigate the relationship between brain tumor risk and ICAM-1 and β3 integrin gene polymorphisms.

MATERIALS AND METHODS

The study covered 92 patients with primary brain tumors and 92 age-matched healthy control subjects. Evaluation of β3 integrin (Leu33Pro (rs5918)) and ICAM-1 (R241G (rs1799969) and K469E (rs5498)) gene polymorphisms was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

According to results of our research, the A allele of the ICAM-1 R241G gene polymorphism appeared to be a risk factor for primary brain tumors (p<0.001). Similarly, the frequency of the A mutant allele of ICAM-1 R241G was statistically significant in patients with brain tumors classified as glioma (p<0.001). When allele and genotype distributions of ICAM- 1 K469E, ICAM-1 R241G and β3 integrin Leu33Pro gene polymorphisms were evaluated with age, sex, and smoking, there were no statistically significant differences. Haplotype analysis revealed that the frequencies of GAC (rs1799969-rs5498-rs5918) and GAT (rs1799969-rs5498-rs5918) haplotypes were significantly lower in patients as compared with controls (p=0.001; p=0.036 respectively).

CONCLUSIONS

This study provides the first evidence that ICAM-1 R241G SNP significantly contributes to the risk of primary brain tumors in a Turkish population. In addition, our results suggest that ICAM-1 R241G in combination ICAM-1 K469E may have protective effects against the development of brain cancer.

Intercellular adhesion molecule-1 gene polymorphisms in patients with familial mediterranean fever

Familial Mediterranean fever (FMF) is a disease of unknown etiology characterized by recurrent attacks of polyserositis and fever. Intercellular adhesion molecule-1 (ICAM-1) is known to contribute inflammatory conditions by regulating leukocyte localization at inflammatory sites. The aim of this study was to evaluate the probable association of ICAM-1 G/R 241 and ICAM-1 E/K 469 polymorphisms according to susceptibility with FMF. Sixty-seven FMF patients and 83 healthy volunteers were included in the study. Genomic DNA was extracted from EDTA-preserved whole blood of whole series of patients and controls, and genotyped by polymerase chain reaction (PCR) and allele-specific oligonucleotide techniques for ICAM-1 polymorphisms G/R at codon 241 and E/K at codon 469. The ICAM-1 241 genotype and allele frequencies of FMF patients and healthy volunteers were similar. The frequency of ICAM-1 K469 homozygosity was significantly lower in FMF patients than in the controls (32.8% vs 50.7% subsequently, p=0.03). Moreover, ICAM-1 E469 allele was more frequent in FMF patients than in controls (44.8% vs 32.3%, p:0.03). Our results showed that ICAM-1 469 gene polymorphism could contribute to the pathogenesis of FMF.

Intercellular adhesion molecule-1 K469E polymorphism in Korean patients with spontaneous preterm delivery

OBJECTIVES

To investigate the association between intercellular adhesion molecule-1 (ICAM-1) gene K469E polymorphism and spontaneous preterm delivery in a Korean population.

METHODS

Genomic DNA was extracted from whole blood from 55 women experiencing preterm labor and 153 multiparous women (control group) with a history of at least 2 term deliveries. DNA samples were analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The spontaneous preterm delivery (SPD) group carried the 469E allele significantly more frequently than those in the control group (odds ratio [OR], 1.62; 95% CI, 1.04-2.53). The EE genotype was significantly associated with increased risk of SPD (OR, 2.84; 95% CI, 1.17-6.89; P = 0.02). Allelic frequencies in women with abnormal C-reactive protein levels (K = 0.48; E = 0.52) were significantly different from frequencies in the controls (K = 0.68; E = 0.32) (P = 0.006).

CONCLUSIONS

ICAM-1 gene K469E polymorphism may be a candidate region and useful predictor of susceptibility to SPD in the Korean population.

Genetic polymorphisms of adhesion molecules in children with severe RSV-associated diseases

Adhesion molecules are involved in the pathophysiology of respiratory syncytial virus (RSV)-associated diseases. By testing polymorphisms within ICAM-1, VCAM-1 and E-selectin, we found no evidence for association of any polymorphism with severe RSV infections. Thus, we conclude that these genes do not predispose to severe RSV-associated diseases.

Dinucleotide repeat polymorphism in intron II of human Toll-like receptor 2 gene and susceptibility to rheumatoid arthritis

Human Toll-like receptors (TLRs) participate in innate immune response and signal the activation of adaptive immunity. The presence of a functional intronic polymorphism consisting of guanine-thymine repeats in TLR2 gene was recently reported. Here, we investigated a dinucleotide repeat polymorphism in intron II of TLR2 in Korean patients with rheumatoid arthritis (RA). The numbers of guanine-thymine [(GT)(n)] repeats in intron II of the TLR 2 gene were counted in 183 patients with RA and in 148 healthy controls, using the gene scanning technique. We classified alleles into two subclasses for further analysis, 12-16 GT repeats (S allele) and 17-28 repeats (L allele). By subgroup analysis, we also examined whether the S allele is associated with the presence of shared epitope (SE), rheumatoid factor (RF), joint erosion and extra-articular complications. S-allele frequency was significantly increased in patients with RA than in healthy controls [30.3% vs. 23.0%, P = 0.03, or 1.46, 95% confidence interval (CI) 1.03-2.07], and genotypes containing S alleles were more frequent in patients with RA than in healthy controls (54.4% vs. 46.5%. P = 0.04, or 1.57, 95% CI 1.01-2.42). A skewed S-allele distribution was not found to be related to the presence of SE. Subgroup analysis showed no genotypic or allele frequency differences between patients with/without RF, joint erosion, or extra-articular complications. Genotype containing shorter GT repeats in intron II of the TLR2 gene may confer susceptibility to RA in Koreans.

ICAM1 amino-acid variant K469E is associated with paediatric bronchial asthma and elevated sICAM1 levels

Intercellular adhesion molecule-1 (ICAM1) acts as ligand for beta2-integrin molecules and mediates leucocyte trafficking to the site of inflammation. Intercellular adhesion molecule-1-deficient mice show impaired lymphocyte recruitment to the lung, less airway hyper-responsiveness and less lung inflammation than healthy controls. Thus, the aim of the study was to test common ICAM1 polymorphisms for association with paediatric asthma. Furthermore, we were interested in whether soluble ICAM1 (sICAM1) serum levels were in correlation with genotypes. The following polymorphisms in ICAM1 were genotyped on 352 children with asthma and 270 controls: rs5491 (resulting in the amino-acid exchange K56M), rs5493 (G241S), rs5498 (K469E), rs5030400 (R478W) and rs885743 in the 3'-untranslated region. In addition, sICAM1 serum levels were measured. Only K469E and rs885743 were present in our populations. K469E showed association with asthma (P = 0.0037 with Armitage's trend test). Haplotype analysis by FAMHAP using both polymorphisms revealed association with asthma by P < 0.000001. In addition, serum sICAM1 levels were correlated with K469E genotypes (P = 0.009 by Kruskal-Wallis test). We conclude from our data that K469KE is associated with paediatric asthma in the German population. Furthermore, the same polymorphism is correlated with serum levels of sICAM1. Functional analyses have to further clarify the pathophysiological mechanism conferred by the polymorphisms.

Understanding the genetic contribution to rheumatoid arthritis

PURPOSE OF REVIEW

The identification of the genetic variants that mediate the risk for susceptibility and severity of rheumatoid arthritis will allow the development of new drug targets and also increase the ability to predict disease course. Technical and methodologic progress has fueled the advances in this field.

RECENT FINDINGS

The second risk factor for rheumatoid arthritis, the PTPN22 polymorphism, has been identified. This genetic variant regulates the threshold of T cell activation. Intriguingly, this variant is a risk factor for diabetes as well. Moreover, it has been shown that multiple genetic variants in one pathway (both in a transcription factor, RUNX-1, as in the transcription factor binding site of RUNX1 in the SLC22A4 gene) can each confer very small risks but by gene-gene interactions can confer a ninefold risk for rheumatoid arthritis. These genetic risk factors have been found to confer risk for multiple autoimmune diseases. Phenotype-genotype interactions were described by the enhanced prevalence of a rheumatoid arthritis-specific autoantibody (anti-cyclic citrullinated peptide antibodies) in rheumatoid arthritis patients that harbor the rheumatoid arthritis-associated human leukocyte antigen class II genes, the shared epitope alleles. An environmental factor, smoking was demonstrated to confer risk for rheumatoid arthritis, especially in patients positive for both shared epitope and rheumatoid arthritis-specific anti-cyclic citrullinated peptide antibodies.

SUMMARY

Two new pathways, T cell receptor signaling and a hematopoietic-specific signal transduction pathway, have been discovered that allow future pharmacologic interventions. The description of the new genetic risk factors and the interaction with environmental triggers as well as phenotypic features are gradually expanding the ability to predict disease susceptibility and course.