Multiple sclerosis association study with the TENR-IL2-IL21 region in a Spanish population

Immunogenetic profiling of 23 SNPs of cytokine and chemokine receptor genes through a minisequencing technique: Design, development and validation

The minisequencing technique offers accuracy and robustness to genotyping of polymorphic DNA variants, being an excellent option for the identification and analyses of prognostic/susceptibility markers in human diseases. Two multiplex minisequencing assays were designed and standardized to screen 23 candidate SNPs in cytokine, chemokine receptor and ligand genes previously associated with susceptibility to cancer and autoimmune disorders as well as to infectious diseases outcome. The SNPs were displayed in two separate panels (panel 1-IL2 rs2069762, TNFα rs1800629, rs361525; IL4 rs2243250; IL6 rs1800795; IL10 rs1800896, rs1800872; IL17A rs8193036, rs2275913 and panel 2-CCR3 rs309125, CCR4 rs6770096, rs2228428; CCR6 rs968334; CCR8 rs2853699; CXCR3 rs34334103, rs2280964;CXCR6 rs223435, rs2234358; CCL20 rs13034664, rs6749704; CCL22 rs4359426; CXCL10/IP-10 rs3921, rs56061981). A total of 305 DNA samples from healthy individuals were genotyped by minisequencing. To validate the minisequencing technique and to encompass the majority of the potential genotypes for all 23 SNPs, 20 of these samples were genotyped by Sanger sequencing. The results of both techniques were 100% in agreement. The technique of minisequencing showed high accuracy and robustness, avoiding the need for high quantities of DNA template samples. It was easily to be conducted in bulk samples derived from a highly admixed human population, being therefore an excellent option for immunogenetic studies.

IL-21 and IL-21 receptor in the immunopathogenesis of multiple sclerosis

Cytokines are considered important factors in the modulation of various immune responses. Among them, interleukin (IL)-21 is one of the major immune modulators, adjusting various immune responses by affecting various immune cells. It has been suggested that IL-21 may enhance autoimmunity through different mechanisms, such as development and activation of helper T (TH)-17 and follicular helper T (TFH) cells, activation of natural killer (NK) cells, enhancing B-cell differentiation and antibody secretion and suppression of regulatory T (Treg) cells. Moreover, IL-21 has also been suggested to be an inducer of autoimmunity when following treatment of MS patients with some therapeutics such as alemtuzumab. This review will seek to clarify the precise role of IL-21/IL-21R in the pathogenesis of MS and, in its animal model, experimental autoimmune encephalomyelitis (EAE).

4q27 as a psoriasis susceptibility locus in the Northeastern Chinese Han population

Psoriasis is an autoimmune inflammatory skin disease with genetic components. Chromosome 4q27 is related to many autoimmune diseases, however, the relationship between psoriasis and 4q27 has not been fully established yet. The objective of this study is to investigate the association between chromosome 4q27 and psoriasis in the Northeastern Chinese Han population. Four common single nucleotide polymorphisms (rs2069762, rs4833837, rs6840978, and rs7684187) from chromosome 4q27 were genotyped in 400 psoriasis cases and 398 controls from the Northeastern Chinese Han population using the Multiplex SNaPSHOT method. Single nucleotide polymorphism and haplotype frequencies were analyzed using spss 13.0. Our data indicated that rs2069762 GG, TG genotypes [GG: odds ratio (OR) = 2.6875, 95% confidence interval (CI) = 1.5948-4.5290, P < 0.0001; TG: OR = 1.6159, 95% CI = 1.2044-2.1681, P = 0.0013], and H3 haplotype (OR = 1.717, 95% CI = 1.050-2.808, P = 0.030) increased the risk of psoriasis. Furthermore, rs4833837 GG, GA genotypes (GG: OR = 0.2071, 95% CI = 0.0685-0.6266, P = 0.0022; GA: OR = 0.4711, 95% CI = 0.3289-0.6746, P < 0.0001), and H5 haplotype (OR = 0.482, 95% CI = 0.238-0.978, P = 0.039) were identified as protective factors for psoriasis. 4q27 polymorphisms are associated with psoriasis in the Northeastern Chinese Han population.

Interleukin-2 and subunit alpha of its soluble receptor in autoimmune Addison's disease--an association study and expression analysis

Autoimmune Addison's disease (AAD) results from T cell-mediated destruction of the adrenal cortex, commonly accompanied by autoantibodies to 21-hydroxylase (21OH). In order to gain insight into the obscure aetiology of this disease, we investigated the roles of the IL2 and IL2RA genes, encoding interleukin-2 and subunit alpha of its receptor (IL2Ra), respectively. The association of AAD with IL2 and IL2RA polymorphisms (rs6822844, rs2069762, rs3136534, rs11594656, rs3118470 and rs2104286) was tested in 223 patients and 672 healthy controls. Functional studies consisted of gene expression analysis in cultured PBMCs exposed to 21OH and evaluation of serum interleukin by ELISA assays. The frequency of the minor C allele of rs3136534 was significantly decreased in AAD subjects compared to controls (OR 0.71; 95%CI 0.561-0.887; p = 0.003). Only AAD cells responded to 21OH with an elevated IL2 and IL2RA mRNA synthesis (p = 0.004 and p = 0.009 versus controls, respectively), paralleled by increased supernatant levels of both cytokines (p = 0.031 and p = 0.001 versus controls). IL2 mRNA level in 21OH-stimulated AAD PBMCs correlated negatively with age (p = 0.036) and positively with serum antibodies to 21OH (p = 0.006). Carriers of the rs2104286 AA genotype demonstrated higher IL2RA mRNA (p = 0.022) and soluble IL2Ra secretion (p = 0.029) upon 21OH stimulation. Serum interleukin-2 in AAD subjects was significantly higher compared to controls (4.61 ± 4.3 versus 1.71 ± 3.2 pg/mL, p < 0.001), whereas sIL2Ra levels remained similar in both groups (p = 0.885). In conclusion, the study reveals an association between AAD and IL2 locus. It confirms specific 21OH-directed reactivity of the peripheral AAD lymphocytes, which display increased synthesis of interleukin-2 and sIL2Ra.

Current concepts in the molecular pathogenesis of thyroid-associated ophthalmopathy

Graves' disease (GD) is a common autoimmune condition. At its core, stimulatory autoantibodies are directed at the thyroid-stimulating hormone receptor (TSHR), resulting in dysregulated thyroid gland activity and growth. Closely associated with GD is the ocular condition known as thyroid-associated ophthalmopathy (TAO). The pathogenesis of TAO remains enigmatic as do the connections between the thyroid and orbit. This review highlights the putative molecular mechanisms involved in TAO and suggests how these insights provide future directions for identifying therapeutic targets. Genetic, epigenetic, and environmental factors have been suggested as contributory to the development of GD and TAO. Thyroid-stimulating hormone receptor and insulin-like growth factor receptor (IGF-1R) are expressed at higher levels in the orbital connective tissue from individuals with TAO than in healthy tissues. Together, they form a functional complex and appear to promote signaling relevant to GD and TAO. Orbital fibroblasts display an array of cell surface receptors and generate a host of inflammatory molecules that may participate in T and B cell infiltration. Recently, a population of orbital fibroblasts has been putatively traced to bone marrow-derived progenitor cells, known as fibrocytes, as they express CD45, CD34, CXCR4, collagen I, functional TSHR, and thyroglobulin (Tg). Fibrocytes become more numerous in GD and we believe traffic to the orbit in TAO. Numerous attempts at developing complete animal models of GD have been largely unsuccessful, because they lack fidelity with the ocular manifestations seen in TAO. Better understanding of the pathogenesis of TAO and development of improved animal models should greatly accelerate the identification of medical therapy for this vexing medical problem.

Polymorphisms of interleukin-21 and interleukin-21-receptor genes confer risk for autoimmune thyroid diseases

BACKGROUND

The abnormality of interleukin-21 (IL-21)-IL-21-receptor (IL-21R) system has been found in many autoimmune diseases including autoimmune thyroid diseases (AITDs). In this study, we investigated whether polymorphisms of the IL-21 and IL-21R are associated with Graves' disease (GD) and Hashimoto's thyroiditis (HT), two major forms of AITDs, among a Chinese population.

METHODS

Rs907715, rs4833837, rs2221903 and rs2055979 of the IL-21 gene and rs3093301 and rs2285452 of the IL-21R gene were explored in a case-control study including 405 GD, 228 HT patients and 242 controls. These genes were genotyped by the PCR and restriction fragment length polymorphism (RFLP) analysis and the MASS spectrometry method.

RESULTS

For IL-21 gene, we identified and confirmed a higher prevalence of A alleles of rs2221903 (P = 0.018, OR = 1.50 95% CI = 1.07-2.09) in GD patients. We also found a significant association between rs2221903 and HT (allele: P = 0.009, OR = 1.69 95% CI = 1.13-2.51; genotype: recessive P = 0.021, OR = 11.72 95% CI = 1.46-94.13). For the IL-21R gene, compared with controls, the genotype frequencies of rs3093301 and rs2285452 were significantly different in HT patients using dominant genetic model (P = 0.023, OR = 1.61 95% CI = 1.07-2.42; P = 0.031, OR = 1.71 95% CI = 1.05-2.80, respectively). Furthermore, the haplotype AA containing the major alleles of rs4833837 and rs2221903 was associated with increased susceptibility to GD with an OR of 1.50(95% CI =1.08-2.09, P = 0.016), and to HT with an OR of 1.69(95% CI =1.14-2.52, P = 0.009).

CONCLUSION

Our results indicated that the SNPs of the IL-21 gene is associated with the development of GD. In addition, we found that individuals with the SNPs of the common IL-21 and IL-21R may have higher risk of HT.

Cerebrospinal fluid IL-21 levels in Neuromyelitis Optica and multiple sclerosis

BACKGROUND

Neuromyelitis optica (NMO) and multiple sclerosis (MS) are inflammatory demyelinating diseases of human central nervous system (CNS) with complex pathogenesis. IL-21/IL-21R regulates activation, proliferation and survival of both T cells and B cells, which are involved in the pathogenesis of NMO and MS. High levels of serum IL-21 were observed in NMO patients. However, concentration of cerebrospinal fluid (CSF) IL-21 in MS and NMO patients still remain unknown.

OBJECT

To detect the CSF concentration of IL-21 in NMO and MS patients and to evaluate its relationship with disease activity, particularly concerned about its impact on humoral immunity.

METHODS

CSF IL-21 was detected by an enzyme-linked immunosorbent assay (ELISA) in NMO patients (n=21), MS patients (n=20) and controls (n=16).

RESULTS

CSF concentration of the IL-21 was noticeably elevated in NMO (p=0.012) and borderline significantly increased in MS (p=0.115). In addition, this occurrence was associated with humoral immune activity as shown by a correlation between IL-21 and complement in NMO cohort (p=0.023) and high IL-21 levels in autoantibody-positive subgroup (p=0.027).

CONCLUSIONS

The concentration of CSF IL-21 was noticeably elevated and might have a positive correlation with humoral immune activity in NMO.

In-vitro characterization of novel and functional regulatory SNPs in the promoter region of IL2 and IL2R alpha in a Gabonese population

Background

The selection pressure imposed by the parasite has a functional consequence on the immune genes, leading to altered immune function in which regulatory T cells (Tregs) induced by parasites during infectious challenges modulate or thwart T effector cell mechanism.

Methods

We identified and investigated regulatory polymorphisms in the immune gene IL2 and its receptor IL2R alpha (also known as CD25) in Gabonese individuals exposed to plentiful parasitic infections.

Results

We identified two reported variants each for IL2 and its receptor IL2R alpha gene loci. Also identified were two novel variants, -83 /-84 CT deletions (ss410961576) for IL2 and -409C/T (ss410961577) for IL2R alpha. We further validated all identified promoter variants for their allelic gene expression using transient transfection assays. Three promoter variants of the IL2 locus revealed no significant expression of the reporter gene. The identified novel variant (ss410961577C/T) of the IL2R alpha revealed a significant higher expression of the reporter gene in comparison to the major allele (P<0.05). In addition, the rs12722616C/T variant of the IL2R alpha locus altered the transcription factor binding site TBP (TATA box binding protein) and C/EBP beta (CCAAT/enhancer binding protein beta) that are believed to regulate the Treg function.

Conclusions

The identification and validation of such regulatory polymorphisms in the immune genes may provide a basis for future studies on parasite susceptibility in a population where T cell functions are compromised.

Compensatory T-cell regulation in unaffected relatives of SLE patients, and opposite IL-2/CD25-mediated effects suggested by coreferentiality modeling

In human systemic lupus erythematosus (SLE), diverse autoantibodies accumulate over years before disease manifestation. Unaffected relatives of SLE patients frequently share a sustained production of autoantibodies with indiscriminable specificity, usually without ever acquiring the disease. We studied relations of IgG autoantibody profiles and peripheral blood activated regulatory T-cells (aTregs), represented by CD4⁺CD25^bright T-cells that were regularly 70–90% Foxp3⁺. We found consistent positive correlations of broad-range as well as specific SLE-associated IgG with aTreg frequencies within unaffected relatives, but not patients or unrelated controls. Our interpretation: unaffected relatives with shared genetic factors compensated pathogenic effects by aTregs engaged in parallel with the individual autoantibody production. To study this further, we applied a novel analytic approach named coreferentiality that tests the indirect relatedness of parameters in respect to multivariate phenotype data. Results show that independently of their direct correlation, aTreg frequencies and specific SLE-associated IgG were likely functionally related in unaffected relatives: they significantly parallelled each other in their relations to broad-range immunoblot autoantibody profiles. In unaffected relatives, we also found coreferential effects of genetic variation in the loci encoding IL-2 and CD25. A model of CD25 functional genetic effects constructed by coreferentiality maximization suggests that IL-2-CD25 interaction, likely stimulating aTregs in unaffected relatives, had an opposed effect in SLE patients, presumably triggering primarily T-effector cells in this group. Coreferentiality modeling as we do it here could also be useful in other contexts, particularly to explore combined functional genetic effects.

Evidence for STAT4 as a common autoimmune gene: rs7574865 is associated with colonic Crohn's disease and early disease onset

Background

Recent studies demonstrated an association of STAT4 variants with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), indicating that multiple autoimmune diseases share common susceptibility genes. We therefore investigated the influence of STAT4 variants on the susceptibility and phenotype of inflammatory bowel diseases (IBD) in a large patient and control cohort.

Methodology/Principal Findings

Genomic DNA from 2704 individuals of Caucasian origin including 857 patients with Crohn's disease (CD), 464 patients with ulcerative colitis (UC), and 1383 healthy, unrelated controls was analyzed for seven SNPs in the STAT4 gene (rs11889341, rs7574865, rs7568275, rs8179673, rs10181656, rs7582694, rs10174238). In addition, a detailed genotype-phenotype analysis was performed. Our analysis revealed an association of the STAT4 SNP rs7574865 with overall decreased susceptibility to CD (p = 0.047, OR 0.86 [95% CI 0.74–0.99]). However, compared to CD patients carrying the wild type genotype, the STAT4 SNP rs7574865 was significantly associated with early CD onset (p = 0.021) and colonic CD (p = 0.008; OR = 4.60, 95% CI 1.63–12.96). For two other STAT4 variants, there was a trend towards protection against CD susceptibility (rs7568275, p = 0.058, OR 0.86 [95% CI 0.74–1.00]; rs10174238, p = 0.057, OR 0.86 [95% CI 0.75–1.00]). In contrast, we did not observe any association with UC susceptibility. Evidence for weak gene-gene interaction of STAT4 with the IL23R SNP rs11209026 was lost after Bonferroni correction.

Conclusions/Significance

Our results identified the STAT4 SNP rs7574865 as a disease-modifying gene variant in colonic CD. However, in contrast to SLE and RA, the effect of rs7574865 on CD susceptibility is only weak.

Analysis of multiple candidate genes in association with phenotypes of multiple sclerosis

Multiple sclerosis is a heterogeneous neurological disease with varying degrees of severity. The common hypothesis is that susceptibility to multiple sclerosis and its phenotype are caused by a combination of environmental and genetic factors. The genetic part exerts its effect through several genes, each having modest effects.

We evaluated whether disease severity could be predicted by a model based on clinical data and data from a DNA chip. The DNA chip was designed containing several single nucleotide polymorphisms in 44 genes, previously described to be associated with multiple sclerosis.

A total of 605 patients with multiple sclerosis were included in this analysis, using gender, onset type and age at onset as clinical covariates. We correlated 80 single nucleotide polymorphisms to the degree of disease severity using the following three outcome measures: linear Multiple Sclerosis Severity Score, dichotomous Multiple Sclerosis Severity Score (using a cut-off point of 2.5) and time to reach Expanded Disability Status Scale score 6.

Sixty-nine single nucleotide polymorphisms were included in the analysis. No individual single nucleotide polymorphism showed a significant association; however, a combination of single nucleotide polymorphisms significantly improved the prediction of disease severity in addition to the clinical variables. In all three models the Interleukin 2 gene was included, confirming a previously reported modest effect on disease severity. The highest power was obtained using the dichotomized Multiple Sclerosis Severity Score as outcome.

Several single nucleotide polymorphisms showed their added predictive value over the clinical data in the predictive models. These results support our hypothesis that disease severity is determined by clinical variables and genetic influences (through several genes with small effects) in concert.

The 4q27 locus and prostate cancer risk

Background

Chronic inflammation is considered to be implicated in the development of prostate cancer. In this study we are the first to investigate a potential association between variants in an autoimmune related region on chromosome 4q27 and prostate cancer risk. This region harbors two cytokine genes IL-2 and the recently described IL-21.

Methods

We genotyped six variants previously associated with autoimmune disease (namely rs13151961, rs13119723, rs17388568, rs3136534, rs6822844 and rs6840978) and one functional IL-2 promoter variant (rs2069762) for possible association with prostate cancer risk using the Australian Risk Factors for Prostate Cancer case-control Study.

Results

Overall, our results do not support an association between the seven variants at position 4q27 and prostate cancer risk. Per allele odds ratios (ORs) were not significantly different from 1 (all P-values = 0.06). However, we found suggestive evidence for a significant association between the presence of the rs13119723 variant (located in a protein of unknown function) and men with a family history of prostate cancer in first-degree relatives (P-value for interaction 0.02). The per allele OR associated with this variant was significantly higher than 1 (2.37; 95% C.I. = 1.01-5.57).

Conclusions

We suggest that genetic variation within the chromosome 4q27 locus might be associated with prostate cancer susceptibility in men with a family history of the disease. Furthermore, our study alludes to a potential role of unknown protein KIAA1109 in conferring this risk.

Polymorphisms in the IL2, IL2RA and IL2RB genes in multiple sclerosis risk

Interleukin (IL)-2/IL-2R signalling promotes proliferation and survival of activated T cells and has an essential non-redundant role in the production of regulatory T cells. Associations with different autoimmune diseases of polymorphisms in a linkage disequilibrium block in which the IL2/IL21 genes map (4q27), and also in genes encoding the IL2RA and IL2RB subunits (located in 10p15 and 22q13, respectively), were identified through genome-wide studies. Polymorphisms in these three genes were studied in 430 multiple sclerosis (MS) patients and in 550 ethnically matched controls from Madrid (Spain). Replication and meta-analysis with results from an independent cohort of 771 MS patients and 759 controls from Andalucía (Spain) confirmed the association of polymorphisms in the IL2RA gene (P(Mantel-Haenszel,) odds ratio (OR)(M-H) (95% confidence interval, CI) for rs2104286: 0.0001, 0.75 (0.65-0.87); for rs11594656/rs35285258: 0.004, 1.19 (1.06-1.34); for rs41295061: 0.03, 0.77 (0.60-0.98)); showed a trend for association of the IL2/IL21 rs6822844 (P(M-H)=0.07, OR(M-H) (95% CI)=0.86 (0.73-1.01)), but did not corroborate the association for IL2RB. Regression analyses of the combined Spanish cohort revealed the independence of two IL2RA association signals: rs2104286 and rs11594656/rs35285258. The relevant role of the IL2RA gene on MS susceptibility adds support to its common effect on autoimmune risk and the suggestive association of IL2/IL21 warrants further investigation.