Investigation of the association of Vogt-Koyanagi-Harada syndrome with IL23R-C1orf141 in Han Chinese Singaporean and ADO-ZNF365-EGR2 in Thai

OR11H1 Missense Variant Confers the Susceptibility to Vogt-Koyanagi-Harada Disease by Mediating Gadd45g Expression

Vogt-Koyanagi-Harada (VKH) disease is a severe autoimmune disease. Herein, whole-exome sequencing (WES) study are performed on 2,573 controls and 229 VKH patients with follow-up next-generation sequencing (NGS) in a collection of 2,380 controls and 2,278 VKH patients. A rare c.188T>C (p Val63Ala) variant in the olfactory receptor 11H1 (OR11H1) gene is found to be significantly associated with VKH disease (rs71235604, Pcombined = 7.83 × 10-30 , odds ratio = 3.12). Functional study showes that OR11H1-A63 significantly increased inflammatory factors production and exacerbated barrier function damage. Further studies using RNA-sequencing find that OR11H1-A63 markedly increased growth arrest and DNA-damage-inducible gamma (GADD45G) expression. Moreover, OR11H1-A63 activates the MAPK and NF-κB pathways, and accelerates inflammatory cascades. In addition, inhibiting GADD45G alleviates inflammatory factor secretion, likely due to the regulatory effect of GADD45G on the MAPK and NF-κB pathways. Collectively, this study suggests that the OR11H1-A63 missense mutation may increase susceptibility to VKH disease in a GADD45G-dependent manner.

The impact of modifier genes on cone-rod dystrophy heterogeneity: An explorative familial pilot study and a hypothesis on neurotransmission impairment

Cone-rod dystrophies (CORDs) are a heterogeneous group of inherited retinopathies (IRDs) with more than 30 already known disease-causing genes. Uncertain phenotypes and extended range of intra- and interfamilial heterogenicity make still difficult to determine a precise genotype-phenotype correlation. Here, we used a next-generation sequencing approach to study a Sicilian family with a suspected form of CORD. Affected family members underwent ophthalmological examinations and a proband, blind from 50 years, underwent whole genome and exome sequencing. Variant analysis was enriched by pathway analysis and relevant variants were, then, investigated in other family members and in 100 healthy controls from Messina. CORD diagnosis with an intricate pattern of symptoms was confirmed by ophthalmological examinations. A total of about 50,000 variants were identified in both proband's genome and exome. All affected family members presented specific genotypes mainly determined by mutated GUCY2D gene, and different phenotypical traits, mainly related to focus and color perception. Thus, we looked for possible modifier genes. According to relationship with GUCY2D, predicted functional effects, eye localization, and ocular disease affinity, only 9 variants, carried by 6 genes (CACNG8, PAX2, RXRG, CCDC175, PDE4DIP and LTF), survived the filtering. These genes encode key proteins involved in cone development and survival, and retina neurotransmission. Among analyzed variants, CACNG8c.*6819A>T and the new CCDC175 c.76C>T showed extremely low frequency in the control group, suggesting a key role on disease phenotypes. Such discovery could enforce the role of modifier genes into CORD onset/progression, contributing to improve diagnostic test towards a better personalized medicine.

Pathogenesis of Non-Infectious Uveitis Elucidated by Recent Genetic Findings

Uveitis is a generic term for inflammation of the uvea, which includes the iris, ciliary body, and choroid. Prevalence of underlying non-infectious uveitis varies by race and region and is a major cause of legal blindness in developed countries. Although the etiology remains unclear, the involvement of both genetic and environmental factors is considered important for the onset of many forms of non-infectious uveitis. Major histocompatibility complex (MHC) genes, which play a major role in human immune response, have been reported to be strongly associated as genetic risk factors in several forms of non-infectious uveitis. Behçet’s disease, acute anterior uveitis (AAU), and chorioretinopathy are strongly correlated with MHC class I-specific alleles. Moreover, sarcoidosis and Vogt-Koyanagi-Harada (VKH) disease are associated with MHC class II-specific alleles. These correlations can help immunogenetically classify the immune pathway involved in each form of non-infectious uveitis. Genetic studies, including recent genome-wide association studies, have identified several susceptibility genes apart from those in the MHC region. These genetic findings help define the common or specific pathogenesis of ocular inflammatory diseases by comparing the susceptibility genes of each form of non-infectious uveitis. Interestingly, genome-wide association of the interleukin (IL)23R region has been identified in many of the major forms of non-infectious uveitis, such as Behçet’s disease, ocular sarcoidosis, VKH disease, and AAU. The interleukin-23 (IL-23) receptor, encoded by IL23R, is expressed on the cell surface of Th17 cells. IL-23 is involved in the homeostasis of Th17 cells and the production of IL-17, which is an inflammatory cytokine, indicating that a Th17 immune response is a common key in the pathogenesis of non-infectious uveitis. Based on the findings from the immunogenetics of non-infectious uveitis, a personalized treatment approach based on the patient’s genetic make-up is expected.

Downregulation of ZNF365 by methylation predicts poor prognosis in patients with colorectal cancer by decreasing phospho-p53 (Ser15) expression

ZNF365 is a transcription factor that plays important roles in different types of cancer, such as colorectal cancer, breast cancer and hepatocellular carcinoma. ZNF365 can promote stalled replication fork recovery to prevent genomic instability, which is a notable feature of sporadic and hereditary types of cancers. However, the function of ZNF365 in the tumor progression of colorectal cancer (CRC) remains unclear. Thus, immunohistochemical staining was used to investigate the association between ZNF365 expression and the clinicopathological characteristics of patients with colorectal cancer. The results demonstrated that ZNF365 protein was strongly expressed in the nucleus and cytoplasm of normal colorectal mucosa. Furthermore ZNF365, which is methylated and downregulated in most cancer cell lines and tissues, was significantly associated with lymph node metastasis (P=0.015), depth of invasion (P=0.031) and histopathological grading (P=0.042). A positive correlation was observed between ZNF365 expression and phosphorylated (P)-p53 (Ser15) protein expression (r=0.18; P=0.038). Survival analysis indicated that patients with high ZNF365 expression had a higher survival rate than those with low ZNF365 expression (P=0.009), suggesting that ZNF365 may be an independent prognostic factor for survival in colorectal cancer (P=0.046). Taken together, the results of the present study demonstrated that ZNF365 was frequently inactivated by promoter methylation and independently predicted poor prognosis in patients with colorectal cancer by downregulating P-p53 (Ser15) expression.

Variants in IL23R-C1orf141 and ADO-ZNF365-EGR2 are associated with susceptibility to Vogt-Koyanagi-Harada disease in Japanese population

Vogt-Koyanagi-Harada (VKH) disease is a systemic inflammatory disorder that affects pigment cell-containing organs such as the eye (e.g., chronic and/or recurrent granulomatous panuveitis). While the exact etiology and pathogenic mechanism of VKH disease are unclear, HLA-DR4 alleles have been documented to be strongly associated with VKH disease in various ethnic groups. Recently, a genome-wide association study (GWAS) found two new genetic risk factors (IL23R-C1orf141 and ADO-ZNF365-EGR2) in a non-HLA region from a Han Chinese population. In this study, we replicated these GWAS findings in a Japanese population. A total of 1,643 Japanese samples (380 cases with VKH disease and 1,263 healthy controls) were recruited. We assessed four single nucleotide polymorphisms (SNPs) shown in previous GWAS: rs78377598 and rs117633859 in IL23R-C1orf141, and rs442309 and rs224058 in ADO-ZNF365-EGR2. A significant allelic association with VKH disease was observed for all of the four SNPs (rs78377598: pc = 0.0057; rs117633859: pc = 0.0017; rs442309: pc = 0.021; rs224058: pc = 0.035). In genotypic association analysis, the minor alleles of IL23R-C1orf141 rs78377598 and rs117633859 had the strongest association with disease susceptibility under the additive model (pc = 0.0075 and pc = 0.0026, respectively). The minor alleles of ADO-ZNF365-EGR2 rs442309 and rs224058 were most strongly associated with disease susceptibility under the dominant model (pc = 0.00099 and pc = 0.0023, respectively). The meta-analysis of the current and previous studies found that all of the four SNPs exhibited a significantly strong association with VKH disease (meta-p < 0.00001: rs78377598, meta-odds ratio (OR) = 1.69; rs1176338, meta-OR = 1.82; rs442309, meta-OR = 1.34; rs224058, meta-OR = 1.33). In summary, our study replicated significant associations with VKH disease susceptibility reported in a previous GWAS. Thus, the IL23R-C1orf141 and ADO-ZNF365-EGR2 loci may play important roles in the development of VKH disease through genetic polymorphisms.

Activation of the interleukin-23/interleukin-17 signalling pathway in autoinflammatory and autoimmune uveitis

Uveitis is a group of diseases characterized by intraocular inflammation, of which some are driven by autoinflammatory or autoimmune responses, such as Vogt-Koyanagi-Harada disease, Behçet's disease, uveitis associated with spondyloarthritis, ocular sarcoidosis, sympathetic ophthalmia and birdshot chorioretinopathy. These entities have various clinical forms, but genetic and biomarker data suggest that they share a common molecular basis, activation of the Interleukin (IL)-23/IL-17 pathway. Multiple factors including genetic predisposition, various cytokine imbalances, infectious agents and gut alterations are found to trigger an aberrant response of this pathway. The enhanced activity of the IL-23/IL-17 pathway is committed to the expansion and pathogenicity of Th17 cells. Evidence from animal models demonstrates that the development of pathogenic Th17 cells is responsible for the induction of experimental autoimmune uveitis. Further findings indicate that retinal pigment epithelium (RPE) cells may be a target of IL-17. IL-17 triggers downstream inflammatory cascades and causes dysfunction of RPE cells, which may affect retinal barrier function and thereby promote intraocular inflammation. Currently, several emerging drugs blocking the IL-23/IL-17 pathway have been assessed for the treatment of uveitis in pilot studies. The purpose of this is to summarize updated biological knowledge and preliminary clinical data, providing the rationale for further development and evaluation of novel drugs targeting the IL-23/IL-17 pathway in autoinflammatory and autoimmune uveitis. Future studies may focus on translational medicine targeting the IL-23/IL-17 pathway for the improvement of diagnosis and treatment of uveitis. In conclusion, activation of the IL-23/IL-17 pathway is a critical biological event and can be an important target for the treatment of autoinflammatory and autoimmune uveitis.

Fine mapping of the GWAS loci identifies SLC35D1 and IL23R as potential risk genes for leprosy

BACKGROUND

Previous genome-wide association study (GWAS) identified two new leprosy associated loci (1p31.3 [rs3762318] and 6q24.3 [rs2275606]). However, there were insufficient validations in independent populations.

OBJECTIVE

To validate the association and to map the potentially causal variants/genes underlying the association between the confirmed GWAS hit and leprosy.

METHODS

We genotyped 10 variants in the regions encompassing the two loci in 1110 Han Chinese subjects with and without leprosy, followed by expression quantitative trait loci (eQTL), mRNA expression profiling, and network analysis. We further sequenced the exon region of four genes that were located in the confirmed GWAS hit region in 80 leprosy patients and 99 individuals without leprosy.

RESULTS

We validated the positive association of rs3762318 with multibacillary leprosy (P=7.5×10^-4), whereas the association of rs2275606 could not be validated. eQTL analysis showed that both the GWAS locus rs3762318 and one surrounding positively associated SNP rs2144658 (P=1.8×10^-3) significantly affected the mRNA expression of a nearby gene SLC35D1, which might be involved in metabolism. Moreover, SLC35D1 was differentially expressed in skin tissues of leprosy patients, and the differential expression pattern was consistent among leprosy subtypes. Rare damaging missense variants in IL23R were significantly enriched in leprosy patients.

CONCLUSION

Our results supported the positive association between the GWAS reported rs3762318 and leprosy, and SLC35D1 and IL23R might be the causal genes.