Soo-Taek Uh

Sequence variants affecting eosinophil numbers associate with asthma and myocardial infarction

Eosinophils are pleiotropic multifunctional leukocytes involved in initiation and propagation of inflammatory responses and thus have important roles in the pathogenesis of inflammatory diseases. Here we describe a genome-wide association scan for sequence variants affecting eosinophil counts in blood of 9,392 Icelanders. The most significant SNPs were studied further in 12,118 Europeans and 5,212 East Asians. SNPs at 2q12 (rs1420101), 2q13 (rs12619285), 3q21 (rs4857855), 5q31 (rs4143832) and 12q24 (rs3184504) reached genome-wide significance (P = 5.3 × 10−14, 5.4 × 10−10, 8.6 × 10−17, 1.2 × 10−10 and 6.5 × 10−19, respectively). A SNP at IL1RL1 associated with asthma (P = 5.5 × 10−12) in a collection of ten different populations (7,996 cases and 44,890 controls). SNPs at WDR36, IL33 and MYB that showed suggestive association with eosinophil counts were also associated with atopic asthma (P = 4.2 × 10−6, 2.2 × 10−5 and 2.4 × 10−4, respectively). We also found that a nonsynonymous SNP at 12q24, in SH2B3, associated significantly (P = 8.6 × 10−8) with myocardial infarction in six different populations (6,650 cases and 40,621 controls).

Role of Reactive Oxygen Species in TGF-β1-Induced Mitogen-Activated Protein Kinase Activation and Epithelial-Mesenchymal Transition in Renal Tubular Epithelial Cells

Epithelial-mesenchymal transition (EMT) plays an important role in renal tubulointerstitial fibrosis and TGF-β1 is the key inducer of EMT. Phosphorylation of Smad proteins and/or mitogen-activated protein kinases (MAPK) is required for TGF-β1–induced EMT. Because reactive oxygen species (ROS) are involved in TGF-β1 signaling and are upstream signaling molecules to MAPK, this study examined the role of ROS in TGF-β1–induced MAPK activation and EMT in rat proximal tubular epithelial cells. Growth-arrested and synchronized NRK-52E cells were stimulated with TGF-β1 (0.2 to 20 ng/ml) or H 2 O 2 (1 to 500 μM) in the presence or absence of antioxidants (N-acetylcysteine or catalase), inhibitors of NADPH oxidase (diphenyleneiodonium and apocynin), mitochondrial electron transfer chain subunit I (rotenone), and MAPK (PD 98059, an MEK [MAP kinase/ERK kinase] inhibitor, or p38 MAPK inhibitor) for up to 96 h. TGF-β1 increased dichlorofluorescein-sensitive cellular ROS, phosphorylated Smad 2, p38 MAPK, extracellular signal-regulated kinases (ERK)1/2, α-smooth muscle actin (α-SMA) expression, and fibronectin secretion and decreased E-cadherin expression. Antioxidants effectively inhibited TGF-β1–induced cellular ROS, phosphorylation of Smad 2, p38 MAPK, and ERK, and EMT. H 2 O 2 reproduced all of the effects of TGF-β1 with the exception of Smad 2 phosphorylation. Chemical inhibition of ERK but not p38 MAPK inhibited TGF-β1–induced Smad 2 phosphorylation, and both MAPK inhibitors inhibited TGF-β1- and H 2 O 2 -induced EMT. Diphenyleneiodonium, apocynin, and rotenone also significantly inhibited TGF-β1–induced ROS. Thus, this data suggest that ROS play an important role in TGF-β1–induced EMT primarily through activation of MAPK and subsequently through ERK-directed activation of Smad pathway in proximal tubular epithelial cells.

A sequence variant on 17q21 is associated with age at onset and severity of asthma

A sequence variant (rs7216389-T) near the ORMDL3 gene on chromosome 17q21 was recently found to be associated with childhood asthma. We sought to evaluate the effect of rs7216389-T on asthma subphenotypes and its correlation with expression levels of neighboring genes. The association of rs7216389-T with asthma was replicated in six European and one Asian study cohort (N=4917 cases N=34 589 controls). In addition, we found that the association of rs7216389-T was confined to cases with early onset of asthma, particularly in early childhood (age: 0–5 years OR=1.51, P=6.89·10−9) and adolescence (age: 14–17 years OR=1.71, P=5.47·10−9). A weaker association was observed for onset between 6 and 13 years of age (OR=1.17, P=0.035), but none for adult-onset asthma (OR=1.07, P=0.12). Cases were further stratified by sex, asthma severity and atopy status. An association with greater asthma severity was observed among early-onset asthma cases (P=0.0012), but no association with sex or atopy status was observed among the asthma cases. An association between sequence variants and the expression of genes in the 17q21 region was assessed in white blood cell RNA samples collected from Icelandic individuals (n=743). rs7216389 associated with the expression of GSDMB and ORMDL3 genes. However, other sequence variants showing a weaker association with asthma compared with that of rs7216389 were more strongly associated with the expression of both genes. Thus, the contribution of rs7216389-T to the development of asthma is unlikely to operate only through an impact on the expression of ORMDL3 or GSDMB genes.

ADAM33 polymorphism : association with bronchial hyper-responsiveness in Korean asthmatics

Background A disintegrin and metalloprotease 33 (ADAM33) is expressed in the lung by fibroblasts and bronchial smooth muscle cells. Given its structure and cellular provenance, ADAM33 may be associated with airway remodelling and bronchial hyper‐responsiveness. Single nucleotide polymorphisms (SNPs) and haplotypes of the ADAM33 gene have previously been associated with asthma susceptibility in the Caucasian population.

Granulocyte macrophage colony-stimulating factor is the main cytokine enhancing survival of eosinophils in asthmatic airways

Interleukin (IL)-3, IL-5 and granulocyte macrophage colony-stimulating factor (GM-CSF) prolong the survival of eosinophils, which are conspicuous in asthmatic airways, but it is still controversial which one plays a major role in enhancing the survival of eosinophils in asthmatic airways. The role of these cytokines in airway eosinophilia was investigated using bronchoalveolar lavage (BAL) fluids from 11 symptomatic and nine asymptomatic patients with asthma and eight normal subjects. Eosinophil survival-enhancing activity (ESEA) was measured by a numerical change in viable eosinophils isolated from the peripheral blood of atopic patients and cultured with BAL fluids. ESEA was characterized by neutralization with antibodies to IL-3, IL-5 and/or GM-CSF. The differential count of BAL cells was achieved using Diff-Quik stain. T-cell subsets and activated T-cells were analysed by flow cytometry with dual stain using monoclonal antibodies to CD3, CD4, CD8 and CD25. ESEA was detected in eight of 11 BAL fluids of symptomatic asthma, but not in those of normal controls or asymptomatic asthmatics. In six symptomatic asthmatics, the mean percentage of inhibition in ESEA by anti-GM-CSF was higher than that of anti-IL-5 as well as anti-IL-3 (p<0.05). A mixture of antibodies to IL-3, IL-5 and GM-CSF totally inhibited the ESEA in four cases. The ESEA correlated with the percentage of eosinophils (p<0.05) and that of CD25(+)CD4 lymphocytes (p<0.05) of BAL cells. In conclusion, granulocyte macrophage colony-stimulating factor, rather than interleukin-3 or -5, is associated with eosinophil survival-enhancing activity inside the airways of symptomatic asthmatics. The activation of CD4 lymphocytes is related to the elevation of such activity.

High-resolution CT findings in patients with near-fatal asthma: comparison of patients with mild-to-severe asthma and normal control subjects and changes in airway abnormalities following steroid treatment.

STUDY OBJECTIVES Extensive airway inflammation and excessive mucus production are implicated in deaths from asthma. High-resolution CT (HRCT) can be used to image both large and small airway abnormalities in asthmatics. The aims of this study were to clarify the distinction of HRCT features between near-fatal asthma (NFA) and non-NFA, and to evaluate serial follow-up HRCT scans of patients with NFA. PATIENTS AND DESIGN Abnormalities of the large airway (bronchial wall thickness) and small airways (prominence of centrilobular structures and air trapping) were measured semiquantitatively on HRCT scans of 24 non-NFA, 16 NFA, and 16 control subjects. In addition, these abnormalities were reevaluated after intensive and relatively long-term (> 6 months) treatment with inhaled corticosteroids. RESULTS Prominence of centrilobular structures was observed in 36% of mild asthma cases, in 70% of moderate-to-severe asthma cases, and in 100% of NFA cases. Prominence of centrilobular structures, but neither bronchial wall thickness nor the area of air trapping, was significantly increased in NFA, as compared with mild or moderate-to-severe asthma (p < 0.05). In the seven non-NFA and five NFA patients who underwent follow-up HRCT scans, only bronchial wall thickness was decreased significantly in the NFA cases (p < 0.05), while bronchial wall thickness and the prominence of centrilobular structures were significantly decreased in the non-NFA cases. These small airway abnormalities were partially reversible in the both groups. Residual prominence of centrilobular structures after long-term inhaled corticosteroid treatment was significantly higher in NFA than non-NFA patients. CONCLUSIONS The results of our study indicate that extensive small airway abnormalities may be associated with NFA, and that these abnormalities are partially reversible after the successful control of asthma symptoms.

Genome-Wide and Follow-Up Studies Identify CEP68 Gene Variants Associated with Risk of Aspirin-Intolerant Asthma

Aspirin-intolerant asthma (AIA) is a rare condition that is characterized by the development of bronchoconstriction in asthmatic patients after ingestion of non-steroidal anti-inflammatory drugs including aspirin. However, the underlying mechanisms of AIA occurrence are still not fully understood. To identify the genetic variations associated with aspirin intolerance in asthmatics, the first stage of genome-wide association study with 109,365 single nucleotide polymorphisms (SNPs) was undertaken in a Korean AIA (n = 80) cohort and aspirin-tolerant asthma (ATA, n = 100) subjects as controls. For the second stage of follow-up study, 150 common SNPs from 11 candidate genes were genotyped in 163 AIA patients including intermediate AIA (AIA-I) subjects and 429 ATA controls. Among 11 candidate genes, multivariate logistic analyses showed that SNPs of CEP68 gene showed the most significant association with aspirin intolerance (P values of co-dominant for CEP68, 6.0×10−5 to 4.0×10−5). All seven SNPs of the CEP68 gene showed linkage disequilibrium (LD), and the haplotype of CEP68_ht4 (T-G-A-A-A-C-G) showed a highly significant association with aspirin intolerance (OR  = 2.63; 95% CI  = 1.64–4.21; P = 6.0×10−5). Moreover, the nonsynonymous CEP68 rs7572857G>A variant that replaces glycine with serine showed a higher decline of forced expiratory volume in 1s (FEV1) by aspirin provocation than other variants (P = 3.0×10−5). Our findings imply that CEP68 could be a susceptible gene for aspirin intolerance in asthmatics, suggesting that the nonsynonymous Gly74Ser could affect the polarity of the protein structure.

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.

Interleukin-13 and Its Receptors in Idiopathic Interstitial Pneumonia: Clinical Implications for Lung Function

Idiopathic interstitial pneumonia (IIP) is characterized by varying degrees of interstitial fibrosis. IL-13 and IL-4 are strong inducers of tissue fibrosis, whereas IFN-γ has antifibrotic potential. However, the roles of these substances in IIP remain unknown. IL-13, IL-4, and IFN-γ were measured in the BAL fluid of 16 idiopathic pulmonary fibrosis (IPF) patients, 10 nonspecific interstitial pneumonia (NSIP) patients, and 8 normal controls. The expression of IL-13 and IL-13Rα1/α2 in lung tissues was analyzed using ELISA and immunohistochemistry. IL-13 levels were significantly higher in IPF patients than the others (P<0.05). IL-4 levels were higher in both IPF and NSIP patients than in normal controls (P<0.05), and IFN-γ levels were lower in NSIP patients than in normal controls (P=0.047). IL-13 levels correlated inversely with FVC% (r=-0.47, P=0.043) and DLCO% (r=-0.58, P=0.014) in IPF and NSIP patients. IL-13 was strongly expressed in the smooth muscle, bronchial epithelium, alveolar macrophages and endothelium of IPF patients. IL-13Rα1, rather than IL-13Rα2, was strongly expressed in the smooth muscle, bronchial epithelium, and endothelium of IPF patients. IL-13 and its receptors may contribute to the pathogenesis of fibrosis in IIP and appear to be related to the severity of the disease.

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.