CD40: Novel Association with Crohn's Disease and Replication in Multiple Sclerosis Susceptibility

Background

A functional polymorphism located at −1 from the start codon of the CD40 gene, rs1883832, was previously reported to disrupt a Kozak sequence essential for translation. It has been consistently associated with Graves'' disease risk in populations of different ethnicity and genetic proxies of this variant evaluated in genome-wide association studies have shown evidence of an effect in rheumatoid arthritis and multiple sclerosis (MS) susceptibility. However, the protective allele associated with Graves'' disease or rheumatoid arthritis has shown a risk role in MS, an effect that we aimed to replicate in the present work. We hypothesized that this functional polymorphism might also show an association with other complex autoimmune condition such as inflammatory bowel disease, given the CD40 overexpression previously observed in Crohn''s disease (CD) lesions.

Methodology

Genotyping of rs1883832C>T was performed in 1564 MS, 1102 CD and 969 ulcerative colitis (UC) Spanish patients and in 2948 ethnically matched controls by TaqMan chemistry.

Principal Findings

The observed effect of the minor allele rs1883832T was replicated in our independent Spanish MS cohort [p = 0.025; OR (95% CI) = 1.12 (1.01–1.23)]. The frequency of the minor allele was also significantly higher in CD patients than in controls [p = 0.002; OR (95% CI) = 1.19 (1.06–1.33)]. This increased predisposition was not detected in UC patients [p = 0.5; OR (95% CI) = 1.04 (0.93–1.17)].

Conclusion

The impact of CD40 rs1883832 on MS and CD risk points to a common signaling shared by these autoimmune conditions.     

Multiple Autoimmune-Associated Variants Confer Decreased IL-2R Signaling in CD4+CD25hi T Cells of Type 1 Diabetic and Multiple Sclerosis Patients

IL-2 receptor (IL-2R) signaling is essential for optimal stability and function of CD4⁺CD25^hiFOXP3⁺ regulatory T cells (Treg); a cell type that plays an integral role in maintaining tolerance. Thus, we hypothesized that decreased response to IL-2 may be a common phenotype of subjects who have autoimmune diseases associated with variants in the IL2RA locus, including T1D and MS, particularly in cells expressing the high affinity IL-2R alpha chain (IL-2RA or CD25). To examine this question we used phosphorylation of STAT5 (pSTAT5) as a downstream measure of IL-2R signaling, and found a decreased response to IL-2 in CD4⁺CD25^hi T cells of T1D and MS, but not SLE patients. Since the IL2RArs2104286 haplotype is associated with T1D and MS, we measured pSTAT5 in controls carrying the rs2104286 risk haplotype to test whether this variant contributed to reduced IL-2 responsiveness. Consistent with this, we found decreased pSTAT5 in subjects carrying the rs2104286 risk haplotype. Reduced IL-2R signaling did not result from lower CD25 expression on CD25^hi cells; instead we detected increased CD25 expression on naive Treg from controls carrying the rs2104286 risk haplotype, and subjects with T1D and MS. However the rs2104286 risk haplotype correlated with increased soluble IL-2RA levels, suggesting that shedding of the IL-2R may account in part for the reduced IL-2R signaling associated with the rs2104286 risk haplotype. In addition to risk variants in IL2RA, we found that the T1D-associated risk variant of PTPN2rs1893217 independently contributed to diminished IL-2R signaling. However, even when holding genotype constant at IL2RA and PTPN2, we still observed a significant signaling defect in T1D and MS patients. Together, these data suggest that multiple mechanisms converge in disease leading to decreased response to IL-2, a phenotype that may eventually lead to loss of tolerance and autoimmunity.     

Inhibitor IκBα promoter functional polymorphisms in patients with multiple sclerosis

The aim of this study is to investigate the association of IκBα promoter polymorphisms with the development of Multiple Sclerosis (MS) disease in Iranian population. One hundred and fifty patients with MS along with 150 unrelated healthy controls were enrolled in this study. The IκBα ?881A/G (rs3138053), ?826C/T (rs2233406) and ?519C/T (rs2233408) polymorphisms were determined by the polymerase chain reaction/restriction fragment length polymorphism method. This study demonstrated that the genotype frequencies of IκBα ?881A/G and ?826T/T, and allele frequencies of IκBα?881G were significantly higher in patients with MS with respect to as compared to the controls. We also found that the estimated haplotype frequency of IκBα promoter ?881G–826T–519C was significantly increased in the patient with MS in comparison with that of the healthy individuals. This study reveals that polymorphisms in the IκBα promoter (?881 A/G, ?826 C/T) are strongly associated with the susceptibility of Iranian MS patients.     

The prevalence of CD33 and MS4A6A variant in Chinese Han population with Alzheimer's disease

CD33 and MS4A6A genes play potential key roles in the pathogenesis of Alzheimer's disease (AD). One recent genome-wide association study has revealed that the rs3865444 polymorphism in the CD33 gene and rs610932 polymorphism in the MS4A6A gene are associated with susceptibility to AD in Caucasians. To evaluate the relationship between the polymorphism of the CD33, MS4A6A gene and AD in the ethnic Chinese Han, we conducted a case-control study (n = 383, age > 54) to determine the prevalence of single-nucleotide polymorphism of two genes in patients with AD in Chinese population of Mainland, and clarified whether these polymorphisms are risk factors for AD. The prevalence of the allele (T) in the rs3865444 polymorphism of the CD33 gene and allele (C) in rs610932 polymorphism of the MS4A6A gene was significantly different in AD patients and control subjects (P < 0.001, respectively), and the results were not influenced by age, gender, or APOE status. Our data revealed the allele (T) of the rs3865444 polymorphism of the CD33 gene and the allele (C) of the rs610932 polymorphism of the MS4A6A gene may contribute to AD risk in the Chinese Han population.     

Roles of Wnt/β-catenin signaling in the gastric cancer stem cells proliferation and salinomycin treatment

The Wnt1 protein, a secreted ligand that activates Wnt signaling pathways, contributes to the self-renewal of cancer stem cells (CSCs) and thus may be a major determinant of tumor progression and chemoresistance. In a series of gastric cancer specimens, we found strong correlations among Wnt1 expression, CD44 expression, and the grade of gastric cancer. Stable overexpression of Wnt1 increased AGS gastric cancer cells'' proliferation rate and spheroids formation, which expressed CSC surface markers Oct4 and CD44. Subcutaneous injection of nude mice with Wnt1-overexpressing AGS cells resulted in larger tumors than injection of control AGS cells. Salinomycin, an antitumor agent, significantly reduced the volume of tumor caused by Wnt1-overexpressing AGS cells in vivo. This is achieved by inhibiting the proliferation of CD44+Oct4+ CSC subpopulation, at least partly through the suppression of Wnt1 and β-catenin expression. Taken together, activation of Wnt1 signaling accelerates the proliferation of gastric CSCs, whereas salinomycin acts to inhibit gastric tumor growth by suppressing Wnt signaling in CSCs. These results suggest that Wnt signaling might have a critical role in the self-renewal of gastric CSCs, and salinomycin targeting Wnt signaling may have important clinical applications in gastric cancer therapy.     

CD209 genetic polymorphism and tuberculosis disease

Background

Tuberculosis causes significant morbidity and mortality worldwide, especially in sub-Saharan Africa. DC-SIGN, encoded by CD209, is a receptor capable of binding and internalizing Mycobacterium tuberculosis. Previous studies have reported that the CD209 promoter single nucleotide polymorphism (SNP)-336A/G exerts an effect on CD209 expression and is associated with human susceptibility to dengue, HIV-1 and tuberculosis in humans. The present study investigates the role of the CD209 -336A/G variant in susceptibility to tuberculosis in a large sample of individuals from sub-Saharan Africa.

Methods and Findings

A total of 2,176 individuals enrolled in tuberculosis case-control studies from four sub-Saharan Africa countries were genotyped for the CD209 -336A/G SNP (rs4804803). Significant overall protection against pulmonary tuberculosis was observed with the -336G allele when the study groups were combined (n = 914 controls vs. 1262 cases, Mantel-Haenszel 2x2 χ² = 7.47, P = 0.006, odds ratio = 0.86, 95%CI 0.77–0.96). In addition, the patients with -336GG were associated with a decreased risk of cavitory tuberculosis, a severe form of tuberculosis disease (n = 557, Pearson''s 2×2 χ² = 17.34, P = 0.00003, odds ratio = 0.42, 95%CI 0.27–0.65). This direction of association is opposite to a previously observed result in a smaller study of susceptibility to tuberculosis in a South African Coloured population, but entirely in keeping with the previously observed protective effect of the -336G allele.

Conclusion

This study finds that the CD209 -336G variant allele is associated with significant protection against tuberculosis in individuals from sub-Saharan Africa and, furthermore, cases with -336GG were significantly less likely to develop tuberculosis-induced lung cavitation. Previous in vitro work demonstrated that the promoter variant -336G allele causes down-regulation of CD209 mRNA expression. Our present work suggests that decreased levels of the DC-SIGN receptor may therefore be protective against both clinical tuberculosis in general and cavitory tuberculosis disease in particular. This is consistent with evidence that Mycobacteria can utilize DC-SIGN binding to suppress the protective pro-inflammatory immune response.     

Polygenic Analysis of Late-Onset Alzheimer’s Disease from Mainland China

Recently, a number of single nucleotide polymorphisms (SNPs) were identified to be associated with late-onset Alzheimer disease (LOAD) through genome-wide association study data. Identification of SNP-SNP interaction played an important role in better understanding genetic basis of LOAD. In this study, fifty-eight SNPs were screened in a cohort of 229 LOAD cases and 318 controls from mainland China, and their interaction was evaluated by a series of analysis methods. Seven risk SNPs and six protective SNPs were identified to be associated with LOAD. Risk SNPs included rs9331888 (CLU), rs6691117 (CR1), rs4938933 (MS4A), rs9349407 (CD2AP), rs1160985 (TOMM40), rs4945261 (GAB2) and rs5984894 (PCDH11X); Protective SNPs consisted of rs744373 (BIN1), rs1562990 (MS4A), rs597668 (EXOC3L2), rs9271192 (HLA-DRB5/DRB1), rs157581 and rs11556505 (TOMM40). Among positive SNPs presented above, we found the interaction between rs4938933 (risk) and rs1562990 (protective) in MS4A weakened their each effect for LOAD; for three significant SNPs in TOMM40, their cumulative interaction induced the two protective SNPs effects lost and made the risk SNP effect aggravate for LOAD. Finally, we found rs6656401-rs3865444 (CR1-CD33) pairs were significantly associated with decreasing LOAD risk, while rs28834970-rs6656401 (PTK2B-CR1), and rs28834970-rs6656401 (PTK2B-CD33) were associated with increasing LOAD risk. In a word, our study indicates that SNP-SNP interaction existed in the same gene or cross different genes, which could weaken or aggravate their initial single effects for LOAD.     

Association of SNPs of CD40 Gene with Multiple Sclerosis in Russians

Multiple sclerosis (MS) is a serious, incurable neurological disease. In 2009, the ANZgene studies detected the suggestive association of located upstream of CD40 gene in chromosome 20q13 (p = 1.3×10⁻⁷). Identification of the causal variant(s) in the CD40 locus leads to a better understanding of the mechanism underlying the development of autoimmune pathologies. We determined the genotypes of rs6074022, rs1883832, rs1535045, and rs11086996 in patients with MS (n = 1684) and in the control group (n = 879). Two SNPs were significantly associated with MS: rs6074022 (additive model C allele OR = 1.27, 95% CI = [1.12–1.45], p = 3×10⁻⁴) and rs1883832 (additive model T allele OR = 1.20, 95% CI = [1.05–1.38], p = 7×10⁻³). In the meta-analysis of our results and the results of four previous studies, we obtain the association p-value of 2.34×10⁻¹², which confirmed the association between MS and rs6074022 at a genome-wide significant level. Next, we demonstrated that the model including rs6074022 only sufficiently described the association. From our analysis, we can speculate that the association between rs1883832 and MS was induced by LD, whereas rs6074022 was a marker in stronger LD with the functional variant or was the functional variant itself. Our results indicated that the functional variants were located in the upstream region of the gene CD40 and were in higher LD with rs6074022 than LD with rs1883832.     

Multivariate Analysis of Dopaminergic Gene Variants as Risk Factors of Heroin Dependence

Background

Heroin dependence is a debilitating psychiatric disorder with complex inheritance. Since the dopaminergic system has a key role in rewarding mechanism of the brain, which is directly or indirectly targeted by most drugs of abuse, we focus on the effects and interactions among dopaminergic gene variants.

Objective

To study the potential association between allelic variants of dopamine D2 receptor (DRD2), ANKK1 (ankyrin repeat and kinase domain containing 1), dopamine D4 receptor (DRD4), catechol-O-methyl transferase (COMT) and dopamine transporter (SLC6A3) genes and heroin dependence in Hungarian patients.

Methods

303 heroin dependent subjects and 555 healthy controls were genotyped for 7 single nucleotide polymorphisms (SNPs) rs4680 of the COMT gene; rs1079597 and rs1800498 of the DRD2 gene; rs1800497 of the ANKK1 gene; rs1800955, rs936462 and rs747302 of the DRD4 gene. Four variable number of tandem repeats (VNTRs) were also genotyped: 120 bp duplication and 48 bp VNTR in exon 3 of DRD4 and 40 bp VNTR and intron 8 VNTR of SLC6A3. We also perform a multivariate analysis of associations using Bayesian networks in Bayesian multilevel analysis (BN-BMLA).

Findings and conclusions

In single marker analysis the TaqIA (rs1800497) and TaqIB (rs1079597) variants were associated with heroin dependence. Moreover, –521 C/T SNP (rs1800955) of the DRD4 gene showed nominal association with a possible protective effect of the C allele. After applying the Bonferroni correction TaqIB was still significant suggesting that the minor (A) allele of the TaqIB SNP is a risk component in the genetic background of heroin dependence. The findings of the additional multiple marker analysis are consistent with the results of the single marker analysis, but this method was able to reveal an indirect effect of a promoter polymorphism (rs936462) of the DRD4 gene and this effect is mediated through the –521 C/T (rs1800955) polymorphism in the promoter.