SLC11A1 gene polymorphisms in Korean patients with Behçet's disease

Clinical trait-specific genetic analysis in Behçet's disease identifies novel loci associated with ocular and neurological involvement

Behçet's disease is a complex inflammatory vasculitis with a broad spectrum of clinical manifestations. The purpose of this study was to investigate the genetics underlying specific clinical features of Behçet's disease. A total of 436 patients with Behçet's disease from Turkey were studied. Genotyping was performed using the Infinium ImmunoArray-24 BeadChip. After imputation and quality control measures, logistic regressions adjusting for sex and the first five principal components were performed for each clinical trait using a case-case genetic analysis approach. A weighted genetic risk score was calculated for each clinical feature. Genetic association analyses of previously identified susceptibility loci in Behçet's disease revealed a genetic association between ocular lesions and HLA-B/MICA (rs116799036: OR = 1.85 [95% CI = 1.35-2.52], p-value = 1.1 × 10-4). The genetic risk score was significantly higher in Behçet's disease patients with ocular lesions compared to those without ocular involvement, which is explained by the genetic variation in the HLA region. New genetic loci predisposing to specific clinical features in Behçet's disease were suggested when genome-wide variants were evaluated. The most significant associations were observed in ocular involvement with SLCO4A1 (rs6062789: OR = 0.41 [95% CI = 0.30-0.58], p-value = 1.92 × 10-7), and neurological involvement with DDX60L (rs62334264: OR = 4.12 [95% CI 2.34 to 7.24], p-value = 8.85 × 10-7). Our results emphasize the role of genetic factors in predisposing to specific clinical manifestations in Behçet's disease, and might shed additional light into disease heterogeneity, pathogenesis, and variability of Behçet's disease presentation across populations.

Epidemiologic and Etiological Features of Korean Patients With Behçet's Disease

Behçet's disease (BD) is a multisystem disease in which environmental factors provoke an adverse immune response in patients with genetic susceptibility towards BD, subsequently leading to a cascade of dysregulated inflammation throughout the body. It is particularly prevalent in regions spanning the ancient Silk Road, including Korea, where the first known case of BD was reported in 1961. We summarize the history, epidemiology, and clinical presentation of BD in Korea, highlighting the clinical tendencies that are particularly seen in the Korean BD population as compared to European populations. Analysis of epidemiologic trends over the past three decades in Korea shows a decreasing prevalence of complete BD and a higher prevalence of intestinal BD. We also discuss the ever-evolving understanding of the pathogenesis of BD, noting the complex interplay among genetics, environment, and immunology. The HLA-B51 allele is the most significant known genetic risk factor in developing BD. We also discuss more recently studied associations between BD and immune factors such as IL-10, IL-23R-IL-12RB2, IL-1A-IL-1B, CCR1, ERAP1, and the GIMAP cluster, the last of which has been found to have an association with BD specifically in Korea. Environmental factors such as pollution and microbials are often the inciting event in developing BD, as they trigger an imbalanced immune response in genetically susceptible individuals, one that has been often found to exhibit an aberrant Th1/Th17 response. There would be value to further studying the pathogenesis and clinical characteristics of Korean BD.

Neutrophil-mediated immune response as a possible mechanism of acute unilateral vestibulopathy

OBJECTIVE

This study aimed to investigate the underlying pathogenesis of acute unilateral vestibulopathy (AUV) using gene expression profiling combined with bioinformatics analysis.

METHODS

Total RNA was extracted from the peripheral blood mononuclear cells of ten AUV patients in the acute phase and from ten controls. The differentially expressed genes (DEGs) between these two groups were screened using microarray analysis with the cut-off criteria (|fold changes| > 1.5 and p-value < 0.05). Functional enrichment analysis of DEGs was performed using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis, and the protein-protein interaction (PPI) network was constructed using the STRING (Search Tool for the Retrieval of Interacting Genes) database.

RESULTS

There were 57 DEGs (50 up-regulated and 7 down-regulated) identified in the AUV group. Functional enrichment analysis showed that most of the up-regulated DEGs were significantly enriched in terms related to the neutrophil-mediated immune pathway. From the PPI network, the top ten hub genes were extracted by calculating four topological properties, and most of them were related to the innate immune system, inflammatory processes and vascular disorders. The complete blood count tests showed that the neutrophil-to-lymphocyte ratio was significantly higher in the 72 AUV patients than in the age-matched controls (2.93±2.25 vs 1.54±0.61, p < 0.001).

CONCLUSIONS

This study showed that the neutrophil-mediated immune pathway may contribute to the development of AUV by mediating inflammatory and thrombotic changes in the vestibular organ.

Molecular Genetic Advances in Uveitis

Uveitis is usually considered as an intraocular inflammation characterized by variety of clinical features. Behcet's disease (BD), Vogt-Koyanagi-Harada (VKH) syndrome, acute anterior uveitis (AAU), and birdshot chorioretinopathy (BCR) are examples of noninfectious forms of uveitis. Although the precise pathogenesis remains unclear, accumulating evidence shows that complex genetic backgrounds coupled with an aberrant immune response may be implicated in the development of uveitis. The complement and pattern recognition systems are both important factors of the innate immune system and are involved in the pathogenesis of uveitis. Copy number variants (CNVs) of complement component 4 have been found to be associated with BD and VKH syndrome, but not with AAU. Several CNVs and gene polymorphisms of toll-like receptors were found to be associated with BD. Leukocytes are an important part of the adaptive immune system and various molecules on these cells play an important role in the development of uveitis. Genes encoding for human leukocyte antigens (HLAs) have been shown to be associated with certain uveitis entities, including BD (HLA-B51), VKH syndrome (HLA-DR4, DRB1/DQA1), AAU (HLA-B27), and BCR (HLA-A29). Genome wide association studies showed that the IL-23R locus was a shared risk factor for multiple uveitis entities including BD, AAU, and VKH syndrome. In addition, various other non-HLA genes are also associated with BD or VKH syndrome, such as IL-10, STAT4, STAT3, and UBAC2. These studies support the hypothesis that genetic factors play a key role in the pathogenesis of uveitis.

SLC11A1 polymorphisms are associated with the risk of chronic obstructive pulmonary disease in a Korean population

The solute carrier family 11 member 1 (SLC11A1) protein plays important roles in macrophage activation and displays pleiotropic effects on various macrophage functions, including the regulation of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and oxidative burst. Considering the important roles of macrophage in the pathogenesis of chronic obstructive pulmonary disease (COPD), we hypothesized that the SLC11A1 gene may act as a low-penetrance susceptibility gene for COPD. To test this hypothesis, we first examined the frequencies of 12 candidate polymorphisms in the SLC11A1 gene in 27 healthy Korean individuals, and then genotyped 3 haplotype-tagging polymorphisms [IVS4 + 14G > C (rs3731865), D543 N (rs17235409), and (*)86A > G (rs1059823)] in 83 COPD patients and 203 healthy controls. Individuals with at least one variant allele of the D543 N and (*)86A > G polymorphisms were at a significantly increased risk for COPD compared with carriers with each homozygous wild-type allele [adjusted odds ratio (OR) = 2.23, 95% confidence interval (CI) = 1.24-4.02, P = 0.007; and adjusted OR = 1.92, 95% CI = 1.10-3.35, P = 0.022, respectively]. Consistent with the findings of the genotyping analysis, the 122 haplotype carrying both the 543 N and (*)86G alleles was associated with a significantly increased risk for COPD compared with the 111 haplotype with the 542D and (*)86A alleles (adjusted OR = 2.05, 95% CI = 1.19-3.51, P = 0.009 and Bonferroni corrected P = 0.027). These findings suggest that the SLC11A1 polymorphisms could be used as markers for genetic susceptibility to COPD. However, further studies with large numbers of subjects are needed to confirm our findings.