Byung Lae Park

Aging and Cytomegalovirus Infection Differentially and Jointly Affect Distinct Circulating T Cell Subsets in Humans

The impact of intrinsic aging upon human peripheral blood T cell subsets remains incompletely quantified and understood. This impact must be distinguished from the influence of latent persistent microorganisms, particularly CMV, which has been associated with age-related changes in the T cell pool. In a cross-sectional cohort of 152 CMV-negative individuals, aged 21–101 y, we found that aging correlated strictly to an absolute loss of naive CD8, but not CD4, T cells but, contrary to many reports, did not lead to an increase in memory T cell numbers. The loss of naive CD8 T cells was not altered by CMV in 239 subjects (range 21–96 y), but the decline in CD4+ naive cells showed significance in CMV+ individuals. These individuals also exhibited an absolute increase in the effector/effector memory CD4+ and CD8+ cells with age. That increase was seen mainly, if not exclusively, in older subjects with elevated anti-CMV Ab titers, suggesting that efficacy of viral control over time may determine the magnitude of CMV impact upon T cell memory, and perhaps upon immune defense. These findings provide important new insights into the age-related changes in the peripheral blood pool of older adults, demonstrating that aging and CMV exert both distinct and joint influence upon blood T cell homeostasis in humans.

Replication of Genetic Effects of FTO Polymorphisms on BMI in a Korean Population

It has been newly reported in recent studies that single‐nucleotide polymorphisms (SNPs) in the first intron of the FTO gene have been associated with BMI in whites. To determine whether the gene is associated with BMI in Asians also, we performed a replication study of the association of the gene with BMI in a Korean population. Two SNPs in the FTO gene (rs1421085 and rs17817449) were genotyped using the TaqMan method in a Korean population (n = 1,733). The two SNPs were then used for an association study with BMI through statistical analyses. The rs1421085 C allele (P = 0.0015, effect size = 0.0056) and rs17817449 G allele (P = 0.0019, effect size = 0.0053) were found to be significantly associated with increased BMI. Our results suggest that FTO may be one of the worldwide obesity‐risk genes.

Association of DNA repair gene XRCC1 polymorphisms with head and neck cancer in Korean population

Squamous cell carcinoma of the head and neck (SCCHN), which is relatively prevalent in Korea, is believed to be induced by environmental carcinogens and host genetic factors. Accumulating evidence has shown that genetic differences in DNA repair capacity resulting from genetic polymorphism influence the risk of environmental carcinogenesis. We therefore examined the associations of genetic polymorphisms in the DNA repair genes XRCC1 with the risk of SCCHN in a Korean population (hospital‐based, case‐control study; 147 cases and 168 controls). Three known polymorphisms in the XRCC1 gene were genotyped: R194W(C>T) in exon 6, R280H(G>A) in exon 9 and R399G(G>A) in exon 10. Although no significant associations were apparent with R280H(G>A) and R399G(G>A), a highly significant association (p = 0.0005) of R194W(C>T) with the increased risk (OR = 2.61; 95% CI 1.53–4.46) of SCCHN was detected among patients and normal controls under dominant model. The frequency of minor allele‐containing genotypes (TT and CT) was much higher in SCCHN patients (51.8%) compared to that in normal controls (30.3%) (p = 0. 0005). When considering a relatively small number of cases (n = 147) and controls (n = 168) in our study, larger studies are needed to validate the genetic effects of XRCC1 polymorphisms in Asian populations. In conclusion, the result from our study provides additional evidence of an association of the XRCC1 polymorphism (Arg194Trp) with SCCHN as markers of genetic susceptibility in the Korean population.

Association of interleukin-6 promoter variant with bone mineral density in pre-menopausal women

AbstractInterleukin-6 (IL6) has many roles essential to the regulation of the immune response, hematopoiesis, and bone resorption. Three single-nucleotide polymorphisms (SNP) in the IL6 promoter region were genotyped by the single-base extension method. The frequencies of each SNP were 0.002 (IL6−597 G→ A), 0.27 (IL6−572 G→ C), and 0.002 (IL6−174 G→ C) in a Korean population (n=1,082). IL6−597 G→ A and IL6−174 G→ C were totally linked together (d2=1) and showed very low allele frequencies (0.002), which are common in Caucasians. On the other hand, the frequency of the IL6−572 G→ C*C allele was much higher (0.27) than that in Caucasian populations (<0.07). One of the IL6 promoter SNPs, viz., IL6−572 G→ C, showed significant associations with bone mineral density (BMD), i.e., the C allele was associated with increased BMD (P=0.02, co-dominant model; P=0.007, dominant model). The mean BMD was highest in homozygous C individuals (0.67±0.15), lowest in homozygous G individuals (0.58±0.19), and intermediate in heterozygotes (0.64±0.21). In the present study, we describe a variant in the IL6 promoter region that shows positive association with higher BMD in a gene-dose-dependent manner in pre-menopausal women.

Polymorphisms in the leptin receptor (LEPR)—putative association with obesity and T2DM

AbstractLeptin plays an important role in regulating adipose-tissue mass. Leptin controls energy balance and food intake through the leptin receptor in the hypothalamus of the brain, which suggests that some polymorphisms of the leptin receptor gene (LEPR) might contribute to obesity or obesity-related diseases. In an effort to identify genetic polymorphisms in a potential candidate gene for obesity and type 2 diabetes mellitus (T2DM) in the Korean population, we have sequenced the LEPR gene. Thirty-five sequence variants were identified (including 9 novel polymorphisms): 1 single nucleotide polymorphism (SNP) in the promoter region, 1 SNP in the 5′ UTR, 8 SNPs in exons (3 non-synonymous SNPs), 23 SNPs in introns, 1 ins/del in the 3′ UTR, and 1 SNP in the 3′ downstream region. To investigate possible association of LEPR polymorphisms with body mass index (BMI) and the risk of T2DM, we genotyped for 11 polymorphisms in the Korean population (n=1,463). Using statistical analyses, no significant associations between the genetic polymorphisms in the LEPR gene and the risk of T2DM were detected. However, one non-synonymous SNP in exon 3, +5193G>A (Arg109Lys), showed marginal association with BMI (P=0.02) and gene dose-dependent genetic effects were observed. The present study provides information about additional genetic polymorphisms in LEPR and positive associations of those polymorphisms with BMI in the Korean population.

A genome-wide association study identified new variants associated with the risk of chronic hepatitis B

UNLABELLED Hepatitis B virus (HBV) infection is the predominant risk factor for chronic hepatitis B (CHB), liver cirrhosis (LC) and hepatocellular carcinoma (HCC). Recently, several genome-wide association studies (GWASs) of CHB identified human leukocyte antigen (HLA) loci, including HLA-DP and HLA-DQ in Asian populations, as being associated with the risk of CHB. To confirm and identify the host genetic factors related to CHB infection, we performed another GWAS using a higher-density chip in Korean CHB carriers. We analyzed 1400 samples from Korean population (400 CHB cases and 1000 population controls) using a higher-density GWAS chip [1 140 419 single nucleotide polymorphisms (SNPs)]. In subsequent replication analysis, we further analyzed in an independent study of a Korean CHB cohort consisting of 2909 Korean samples (971 cases and 1938 controls). Logistic regression methods were used for statistical analysis adjusting for age and sex as covariates. This study identified two new risk-associated loci for CHB on the HLA region of chromosome 6, e.g. rs652888 on euchromatic histone-lysine-methyltransferase 2 (EHMT2, P = 7.07 × 10(-13)) and rs1419881 on transcription factor 19 (TCF19, P = 1.26 × 10(-18)). Conditional analysis with nearby HLA CHB loci that were previously known, confirmed the independent genetic effects of these two loci on CHB. CONCLUSION The GWAS and the subsequent validation study identified new variants associated with the risk of CHB. These findings may advance the understanding of genetic susceptibility to CHB.

Interleukin 3 (IL3) polymorphisms associated with decreased risk of asthma and atopy.

AbstractCytokines, having central functions in immunological and inflammatory process, are always expected to play important roles in the pathogenesis of various diseases, such as asthma. Genetic polymorphisms of those cytokine and cytokine receptor genes are the focus of genetic association studies. In an effort to identify gene(s) whose variant(s) are involved in the development of asthma, we examined the genetic effects of 19 single nucleotide polymorphisms in eight cytokine and cytokine receptor genes, including IL1A, IL1B, IL2, IL3, IL4, IL8, IL10, and IL5RA, on asthma and atopy. Nineteen single nucleotide polymorphisms in eight cytokine and cytokine receptor genes were genotyped using the single-base extension method in a Korean asthma cohort (n=723). Logistic regression and multiple regressions were used for statistical analyses controlling for smoking, age, and gender as covariables. Genetic association analysis of polymorphisms revealed that one exonic (exon 1), IL3+79T>C (Ser27Pro), showed significant association with the risk of asthma and atopy. The Pro allele had shown dominant and protective effects on development of asthma in nonatopic subjects (P=0.002) and also showed significant association with the risk of atopy in normal control subjects (P=0.007). This information about the genetic association of important genes with asthma might provide valuable insights into strategies for the pathogenesis of asthma and atopy.

Association between interleukin 6 promoter variants and chronic hepatitis B progression

Interleukin 6 (IL6) plays an essential role in the regulation of immune response to chronic disease. In this study, the three known single nucleotide polymorphisms (SNPs) in the IL6 promoter region were genotyped in a large chronic hepatitis B cohort to evaluate the effects of IL6 promoter variants. The single base extension method was used for this genotyping. Haplotypes were constructed by the three SNPs in IL6. Allele frequencies were compared for; i) patients with chronic hepatitis (CH) and chronic carriers vs. chronic hepatis patients with clinical evidence of liver cirrhosis (LC) (i.e., portal hypertension), ii) cirrhotic patients with hepatocellular carcinoma (HCC) vs. without HCC by logistic regression, and iii) with respect to the time intervals from the onset of infection to HCC. Results were analyzed by Cox relative hazard analysis on the assumption that all the patients were infected during early infancy. The frequencies of each SNP were 0.002 (IL6-597 G>A), 0.25 (IL6-572 C>G) and 0.002 (IL6-174 G>C), respectively, in the Korean population (n = 1,046). No significant associations were detected between IL6-572 C>G and chronic hepatitis B outcome in this study; i.e., chronic hepatitis B outcome in this study; i.e., LC occurrence on CH (OR = 0.16-1.27, P = 0.13- 0.71) and HCC occurrence on LC (OR = 1.04-1.23, P = 0.89-0.60) of heterozygotes and homozygotes for G allele in referent comparison to homozygotes for common allele (C/C genotype), and time interval to HCC (RH = 0.67-1.00; P = 0.14-0.99). In conclusion, there appeared to be no significant associations between IL6 promoter variants and disease outcome in chronic hepatitis B.

Association of IL-17RB Gene Polymorphism With Asthma

BACKGROUND Interleukin (IL)-17E is a member of the IL-17 family, which induces IL-4, IL-5, IL-13, and eotaxin in experimental animals via IL-17 receptor B (IL-17RB). The activation of IL-17RB amplifies allergic-type inflammatory responses by inducing Jun kinase (or JNK), p38 mitogen-activated protein kinase (or MAPK), and nuclear factor-kappaB. OBJECTIVES We examined the association of polymorphisms in the IL-17RB gene with asthma susceptibility and investigated the effects of those polymorphisms on the transcription of various IL-17RB isoforms. METHODS In total, 954 asthmatic patients or 265 healthy control subjects were screened for polymorphisms in IL-17RB by single-base extension. The messenger RNA expression IL-17RB in B-cell lines derived from patients was also measured by reverse transcription-polymerase chain reaction. RESULTS Direct sequencing of 24 unrelated Korean DNA samples revealed 18 genetic variants, including four insertion/deletions and 14 single-nucleotide polymorphisms (SNPs). Six of the SNPs (-1465G>A, +5661G>A, +6297T>C [Y123Y], +13797C>T, +18661C>T, and +18965G>A) were used to screen a larger group of subjects. Intronic polymorphism +5661G>A was significantly associated with the development of asthma (p = 0.001); moreover, a minor allele of IL-17RB +5661G>A appeared at a lower frequency in the asthmatic patients than in the healthy control subjects (0.13 vs 0.19, respectively). The IL-17RB messenger RNA expression in B cells homozygous for IL-17RB+ 5661GG was significantly higher than that in B cells homozygous for IL-17RB+5661AA (p = 0.002). CONCLUSIONS A rare allele of IL-17RB +5661G>A may have a protective role against the development of asthma via regulation at the level of transcription. The SNPs identified in this study may be used to develop markers to assess the risk of asthma.

Association study of semaphorin 7a (sema7a) polymorphisms with bone mineral density and fracture risk in postmenopausal Korean women

AbstractBone mineral density (BMD), the major factor determining bone strength, is closely related to osteoporotic fracture risk and is determined largely by multiple genetic factors. Semaphorin 7a (SEMA7A), a recently described member of the semaphorin family, has been shown to play a critical role in the activation of monocyte/macrophages that share progenitors with bone-resorbing osteoclasts and thus might contribute to osteoclast development. In the present study, we directly sequenced theSEMA7A gene in 24 Korean individuals, and identified 15 sequence variants. Five polymorphisms (+15667G>A, +15775C>G, +16285C>T, +19317C>T, +22331A>G) were selected and genotyped in postmenopausal Korean women (n=560) together with measurement of the areal BMD (g/cm2) of the anterior-posterior lumbar spine and the non-dominant proximal femur using dual-energy X-ray absorptiometry. We found that polymorphisms of the SEMA7A gene were associated with the BMD of the lumbar spine and femoral neck. SEMA7A+15775C>G and SEMA7A+22331A>G were associated with low BMD of the femoral neck (P=0.02) and lumbar spine (P=0.04) in a recessive model. SEMA7A-ht4 also showed an association with risk of vertebral fracture (OR=1.87-1.93, P=0.02-0.03). Our results suggest that variations in SEMA7A may play a role in decreased BMD and risk of vertebral fracture.