Association analyses identifying two common susceptibility loci shared by psoriasis and systemic lupus erythematosus in the Chinese Han population.

BACKGROUND: Genome-wide association studies (GWASs) have revealed a large number of genetic risk loci for many autoimmune diseases. One clear finding emerging from the published genetic studies of autoimmunity is that different autoimmune diseases, such as psoriasis and systemic lupus erythematosus (SLE), share susceptibility loci. Our study explores additional susceptibility loci shared by psoriasis and SLE in the Chinese Han population. METHODS: In total, 20 single nucleotide polymorphisms (SNPs) in 17 previously reported psoriasis susceptibility loci and 34 SNPs from 24 previously reported SLE susceptibility loci were investigated in our initial psoriasis and SLE GWAS dataset. Among these SNPs, we selected two SNPs (rs8016947 and rs4649203) with association values of p<5×10(-2) for both diseases in the GWAS data for further investigation in psoriasis (7260 cases and 9842 controls) and SLE (2207 cases and 9842 controls) using a Sequenom MassARRAY system. RESULTS: We found that these two SNPs (rs8016947 and rs4649203) in two loci (NFKBIA and IL28RA) were associated with psoriasis and SLE with genome-wide significance (Pcombined<5×10(-8) in psoriasis and Pcombined<5×10(-8) in SLE): rs8016947 at NFKBIA (Pcombined-psoriasis=3.90×10(-10), Pcombined-SLE=1.08×10(-13)) and rs4649203 at IL28RA (Pcombined-psoriasis=3.91×10(-12), Pcombined-SLE=9.90×10(-9)). CONCLUSIONS: These results showed that two common susceptibility loci (NFKBIA and IL28RA) are shared by psoriasis and SLE in the Chinese Han population.

Identification and Characterization of Two Novel Alpha-D-Galactosidases from Pedobacter heparinus.

Two putative α-D-galactosidases (α-GALs) belonging to glycosyl hydrolase family 27, and originating from the rather unexplored bacterial strain Pedobacter heparinus, were cloned and biochemically characterized. The recombinant enzymes designated as PhAGal729 and PhAGal2920 showed comparable biochemical properties: the optimum pH values were determined to be pH 5.0 and 5.5, and temperature optima lay between 30°C and 37°C, respectively. Both α-GALs were not dependent on the presence of divalent metal ions, and the addition of EDTA had no influence on enzymatic activity. The activity of both enzymes substantially increased in the presence of Fe3(+) ions. Both enzymes were inhibited by sodium dodecyl sulfate (SDS) and urea. α-GALs from P. heparinus were highly specific in hydrolyzing glycosides with α-1,2/3/4 or α-1,6-linked galactose to other sugars, whereas other glycosides such as α-linked N-acetylgalactosamine, N-acetylglucosamine or glucose residues were not released. Nevertheless, neither PhAGal729 nor PhAGal2920 were able to remove α-linked galactose epitopes from native human erythrocytes. The facile expression and purification procedures in combination with wide substrate specificities make α-GALs from P. heparinus potential candidates for applications in analytical research, and food- and biotechnology.

Complement C4 induces regulatory T cells differentiation through dendritic cell in systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is a prototypic systemic autoimmune disease. Complement component 4 (C4) has be proved to play a role in pathogenesis of SLE. In the present study, we investigated the effect of C4 on T cells differentiation. METHODS: Thirty SLE patients were included in this study. CD4+ T cells were isolated from healthy subjects, and dendritic cells (DCs) were isolated from healthy subjects or SLE patients. C4 was supplemented to co-incubate with T cells and DCs. RESULTS: Serum C4 concentration was positively correlated with regulatory T cell (Treg) percentage (R(2) = 0.5907, p < 0.001) and TGFß concentration (R(2) = 0.5641, p < 0.001) in SLE patients. Different concentrations of C4 had no effect on T cells differentiation. Co-incubated T cells with DCs and C4 for 7 days, the Treg percentage and TGF-ß concentration were significantly elevated. In addition, pre-treated DCs (from healthy subjects or SLE patients) with C4 and then co-incubated with T cells, the increases of Treg percentage and TGF-ß concentration were also observed. CONCLUSION: C4 takes part in T cells differentiation to Treg cells via DCs.

A simple oligonucleotide biochip capable of rapidly detecting known mitochondrial DNA mutations in Chinese patients with Leber's hereditary optic neuropathy (LHON).

Leber's hereditary optic neuropathy (LHON) is a maternally transmitted disease. Clinically, no efficient assay protocols have been available. In this study, we aimed to develop an oligonucleotide biochip specialized for detection of known base substitution mutations in mitochondrial DNA causing LHON and to investigate frequencies of LHON relevant variants in Anhui region of China. Thirty-two pairs of oligonucleotide probes matched with the mutations potentially linked to LHON were covalently immobilized. Cy5-lablled targets were amplified from blood DNA samples by a multiplex PCR method. Two kinds of primary mutations 11778 G > A and 14484 T > C from six confirmed LHON patients were interrogated to validate this biochip format. Further, fourteen Chinese LHON pedigrees and twenty-five unrelated healthy individuals were investigated by the LHON biochip, direct sequencing and pyrosequencing, respectively. The biochip was found to be able efficiently to discriminate homoplasmic and heteroplasmic mtDNA mutations in LHON. Biochip analysis revealed that twelve of eighteen LHON symptomatic cases from the 14 Chinese pedigree harbored the mutations either 11778G > A, 14484T > C or 3460G > A, respectively, accounting for 66.7%. The mutation 11778G > A in these patients was homoplasmic and prevalent (55.5%, 10 of 18 cases). The mutations 3460G > A and 3394T > C were found to co-exist in one LHON case. The mutation 13708G > A appeared in one LHON pedigree. Smaller amount of sampling and reaction volume, easier target preparation, fast and high-throughput were the main advantages of the biochip over direct DNA sequencing and pyrosequencing. Our findings suggested that primary mutations of 11778G > A, 14484T > C or 3460G > A are main variants of mtDNA gene leading to LHON in China. The biochip would easily be implemented in clinical diagnosis.

Psoriasis regression analysis of MHC loci identifies shared genetic variants with vitiligo.

Psoriasis is a common inflammatory skin disease with genetic components of both immune system and the epidermis. PSOR1 locus (6q21) has been strongly associated with psoriasis; however, it is difficult to identify additional independent association due to strong linkage disequilibrium in the MHC region. We performed stepwise regression analyses of more than 3,000 SNPs in the MHC region genotyped using Human 610-Quad (Illumina) in 1,139 cases with psoriasis and 1,132 controls of Han Chinese population to search for additional independent association. With four regression models obtained, two SNPs rs9468925 in HLA-C/HLA-B and rs2858881 in HLA-DQA2 were repeatedly selected in all models, suggesting that multiple loci outside PSOR1 locus were associated with psoriasis. More importantly we find that rs9468925 in HLA-C/HLA-B is associated with both psoriasis and vitiligo, providing first important evidence that two major skin diseases share a common genetic locus in the MHC, and a basis for elucidating the molecular mechanism of skin disorders.

Genome-wide association study identifies two new susceptibility loci for atopic dermatitis in the Chinese Han population.

Atopic dermatitis is a chronic, relapsing form of inflammatory skin disorder that is affected by genetic and environmental factors. We performed a genome-wide association study of atopic dermatitis in a Chinese Han population using 1,012 affected individuals (cases) and 1,362 controls followed by a replication study in an additional 3,624 cases and 12,197 controls of Chinese Han ethnicity, as well as 1,806 cases and 3,256 controls from Germany. We identified previously undescribed susceptibility loci at 5q22.1 (TMEM232 and SLC25A46, rs7701890, P(combined) = 3.15 × 10(-9), odds ratio (OR) = 1.24) and 20q13.33 (TNFRSF6B and ZGPAT, rs6010620, P(combined) = 3.0 × 10(-8), OR = 1.17) and replicated another previously reported locus at 1q21.3 (FLG, rs3126085, P(combined) = 5.90 × 10(-12), OR = 0.82) in the Chinese sample. The 20q13.33 locus also showed evidence for association in the German sample (rs6010620, P = 2.87 × 10(-5), OR = 1.25). Our study identifies new genetic susceptibility factors and suggests previously unidentified biological pathways in atopic dermatitis.

Genome-wide association study for vitiligo identifies susceptibility loci at 6q27 and the MHC.

We conducted a genome-wide association study of generalized vitiligo in the Chinese Han population by genotyping 1,117 cases and 1,429 controls. The 34 most promising SNPs were carried forward for replication in samples from individuals of the Chinese Han (5,910 cases and 9,916 controls) and Chinese Uygur (713 cases and 824 controls) populations. We identified two independent association signals within the major histocompatibility complex (MHC) region (rs11966200, Pcombined=1.48x10(-48), OR=1.90; rs9468925, Pcombined=2.21x10(-33), OR=0.74). Further analyses suggested that the strong association at rs11966200 might reflect the reported association of the HLA-A*3001, HLA-B*1302, HLA-C*0602 and HLA-DRB1*0701 alleles and that the association at rs9468925 might represent a previously unknown HLA susceptibility allele. We also identified one previously undescribed risk locus at 6q27 (rs2236313, Pcombined=9.72x10(-17), OR=1.20), which contains three genes: RNASET2, FGFR1OP and CCR6. Our study provides new insights into the genetic basis of vitiligo.

The analysis of genetics and associated autoimmune diseases in Chinese vitiligo patients.

Vitiligo is a common skin and hair depigmentary disorder that results from selective destruction of melanocytes. It occurs in a typical multifactorial, polygenic inheritance. Several studies have indicated that vitiligo is associated with some autoimmune diseases. In this paper we examined 6,516 vitiligo patients including clinical characteristics, familial involvement, and their association with other autoimmune diseases. Compared with sporadic vitiligo probands, familial vitiligo probands have earlier age onset and longer disease duration. The prevalences of four autoimmune diseases namely rheumatoid arthritis, chronic urticaria, alopecia areata and psoriasis, were significantly elevated in generalized vitiligo probands and their first-degree relatives. The prevalences of chronic urticaria, rheumatoid arthritis, psoriasis were much higher in familial generalized vitiligo probands. In addition, the prevalences of diabetes mellitus and asthma were also higher in familial vitiligo probands. These findings indicate that generalized vitiligo may share common genetic aetiologic links with other autoimmune diseases, and the genetic component of familial generalized vitiligo is stronger.