Cytokine gene polymorphisms and susceptibility to juvenile idiopathic arthritis. British Paediatric Rheumatology Study Group

New discoveries in the genetics and genomics of systemic juvenile idiopathic arthritis

INTRODUCTION

Systemic juvenile idiopathic arthritis (sJIA) is a severe inflammatory condition with onset in childhood. It is sporadic, but elements of its stereotypical innate immune responses are likely genetically encoded by both common variants with small effect sizes and rare variants with larger effects.

AREAS COVERED

Genomic investigations have defined the unique genetic architecture of sJIA. Identification of the class II HLA locus as the strongest sJIA risk factor for the first time brought attention to T lymphocytes and adaptive immune mechanisms in sJIA. The importance of the human leukocyte antigen (HLA) locus was reinforced by recognition that HLA-DRB1*15 alleles are strongly associated with development of drug reactions and sJIA-associated lung disease (sJIA-LD). At the IL1RN locus, genetic variation relates to both risk of sJIA and may also predict non-response to anakinra. Finally, rare genetic variants may have critical roles in disease complications, such as homozygous LACC1 mutations in families with an sJIA-like illness, and hemophagocytic lymphohistiocytosis (HLH) gene variants in some children with macrophage activation syndrome (MAS).

EXPERT OPINION

Genetic and genomic analysis of sJIA holds great promise for both basic discovery of the course and complications of sJIA, and may help guide personalized medicine and therapeutic decision-making.

Association between Interleukin-17F 7488A/G and 7383A/G polymorphisms and susceptibility to juvenile idiopathic arthritis

BACKGROUND

Interleukin-17F (IL-17F), one of the cytokines, is crucial in the pathophysiology of juvenile idiopathic arthritis (JIA). Therefore, we aimed to determine the relation between IL17F 7488A/G and IL17F 7383A/G single-nucleotide polymorphisms and JIA susceptibility and to explain their impact on the disease activity.

METHODS

Genomic DNA of 70 patients with JIA and 70 age and sex-matched controls were extracted and typed for IL17F 7488A/G and IL17F 7383A/G single-nucleotide polymorphisms, using polymerase chain reaction with sequence-specific primers method, and compared between patients and controls.

RESULTS

When compared to AA participants, children with the AG genotype of the IL17F 7488A/G and IL17F 7383A/G polymorphisms showed a substantially greater risk of JIA. Furthermore, children with the G allele were 2.8 folds more likely to have JIA than the A allele for IL17F 7488A/G polymorphism and 3.72 folds for IL17F 7383A/G polymorphism. Children with AG genotype of IL17F 7383A/G polymorphism were far more likely to have high activity JIA.

CONCLUSIONS

The G allele of both IL17F 7488A/G and IL17F7383 A/G polymorphisms is associated with increased JIA susceptibility, and JIA at High Disease Activity was more likely to develop in AG subjects of the IL17F 7383 A/G polymorphism.

IMPACT

The relationship between Interleukin-17F 7488A/G and 7383A/G polymorphisms and risk for JIA has not been recognized before. Impact of Interleukin-17F 7488A/G and 7383A/G genotypes on JIA disease activity. The G allele of both IL17F 7488A/G and IL17F7383 A/G polymorphisms are associated with increased JIA susceptibility. AG genotype of Interleukin-17F 7383 A/G polymorphism compared to AA patients, had a higher probability of developing JIA at a High Disease Activity (HDA) level.

SPOP targets the immune transcription factor IRF1 for proteasomal degradation

Adaptation of the functional proteome is essential to counter pathogens during infection, yet precisely timed degradation of these response proteins after pathogen clearance is likewise key to preventing autoimmunity. Interferon regulatory factor 1 (IRF1) plays an essential role as a transcription factor in driving the expression of immune response genes during infection. The striking difference in functional output with other IRFs is that IRF1 also drives the expression of various cell cycle inhibiting factors, making it an important tumor suppressor. Thus, it is critical to regulate the abundance of IRF1 to achieve a 'Goldilocks' zone in which there is sufficient IRF1 to prevent tumorigenesis, yet not too much which could drive excessive immune activation. Using genetic screening, we identified the E3 ligase receptor speckle type BTB/POZ protein (SPOP) to mediate IRF1 proteasomal turnover in human and mouse cells. We identified S/T-rich degrons in IRF1 required for its SPOP MATH domain-dependent turnover. In the absence of SPOP, elevated IRF1 protein levels functionally increased IRF1-dependent cellular responses, underpinning the biological significance of SPOP in curtailing IRF1 protein abundance.

Interferon-α2a induces CD4+ T cell apoptosis and suppresses Th1/Th17 responses via upregulating IRF1-mediated PDL1 expression in dendritic cells from Behcet's uveitis

Recombinant interferon-α2a (IFNα2a) has been widely used in the treatment of Behcet's uveitis (BU). However, the mechanism underlying its effects remains poorly understood. In this study, we investigated its effect on dendritic cells (DCs) and CD4⁺ T cells, which are essential for the development of BU. Our results showed that the expression of PDL1 and IRF1 was significantly decreased in DCs from active BU patients, and IFNα2a could significantly upregulate PDL1 expression in an IRF1-dependent manner. IFNα2a-treated DCs induced CD4⁺ T cells apoptosis and inhibited the Th1/Th17 immune response in association with reduced secretion of IFN-γ and IL-17. We also found that IFNα2a promoted Th1 cell differentiation and IL-10 secretion by CD4⁺ T cells. Finally, a comparison of patients before and after IFNα2a therapy revealed that the frequencies of Th1/Th17 cells significantly decreased in association with remission of uveitis after IFNα2a therapy. Collectively, these results show that IFNα2a could exert its effects by modulating the function of DCs and CD4⁺ T cells in BU.

The association between interleukin-6 promoter polymorphisms and rheumatoid arthritis by ethnicity: A meta-analysis of 33 studies

OBJECTIVE

We performed a meta-analysis to determine the effect Interleukin-6 (IL-6) promoter polymorphism (-174 G>C, -572 G>C, and -597 G>A) have on the development rheumatoid arthritis (RA) by ethnicity.

MATERIAL AND METHODS

PubMed, EBSCO, LILACS, and Scopus databases were searched for studies exploring the association between any IL6 polymorphisms and RA until November 2018. Genotype distributions were extracted and, depending on the level heterogeneity, determined by the ψ²-based Q test and the Inconsistency Index (I²), fixed-effects or random-effects models were used to calculate pooled odds ratios (ORs) with 95% confidence intervals (95%CIs) for the heterozygous, homozygous, dominant, recessive, and allelic genetic models.

RESULTS

From 708 identified publications, 33 were used in this analysis. For the -174 polymorphism, Asians (OR_heterozygous=7.57, 95%CI: 2.28-25.14, OR_homozygous=5.84, 95%CI: 2.06-16.56, OR_dominant=7.21, 95%CI: 2.30-22.63, OR_recessive=5.04, 95%CI: 1.78-14.28, OR_allelic=6.60, 95%CI: 2.26-19.28, p<.05) and Middle East countries (OR_heterozygous=2.30, 95%CI: 1.10-4.81, OR_dominant=2.27, 95%CI: 1.22-4.22, OR_allelic=2.29, 95%CI: 1.24-4.23, p<.05) were associated with a significant risk of developing RA. Whereas, for Latinos, the C-allele was associated with a benefit (OR_homozygous=0.26, 95%CI: .08-.82, OR_recessive=.25, 95%CI: .08-.80, p<.05). For the -572 polymorphism, Asians demonstrated a significant association for the homozygous and recessive genetic models (8 studies, OR_homozygous=1.56, 95%CI: 1.16-2.09, OR_recessive=1.63, 95%CI: 1.08-2.45, p<.05). For the -597 polymorphism, no association was observed.

CONCLUSIONS

Here, the -174 G>C polymorphism increased the risk of developing RA in Asians and Middle East populations. Interestingly, for Latinos, the polymorphism was associated with a benefit. For the -572 polymorphism, only the Asian population showed an increased risk of developing RA for the CC genotype.

Juvenile Idiopathic Arthritis Associated Uveitis

Juvenile idiopathic arthritis (JIA) is the most common childhood rheumatic disease. The development of associated uveitis represents a significant risk for serious complications, including permanent loss of vision. Initiation of early treatment is important for controlling JIA-uveitis, but the disease can appear asymptomatically, making frequent screening procedures necessary for patients at risk. As our understanding of pathogenic drivers is currently incomplete, it is difficult to assess which JIA patients are at risk of developing uveitis. Identification of specific risk factors for JIA-associated uveitis is an important field of research, and in this review, we highlight the genomic, transcriptomic, and proteomic factors identified as potential uveitis risk factors in JIA, and discuss therapeutic strategies.

The Association Between Interleukin-6 Promoter Polymorphisms and Rheumatoid Arthritis by Ethnicity: A Meta-Analysis of 33 Studies

OBJECTIVE

We performed a meta-analysis to determine the effect Interleukin-6 (IL-6) promoter polymorphism (-174 G>C, -572 G>C, and -597 G>A) have on the development rheumatoid arthritis (RA) by ethnicity.

MATERIAL AND METHODS

PubMed, EBSCO, LILACS, and Scopus databases were searched for studies exploring the association between any IL6 polymorphisms and RA until November 2018. Genotype distributions were extracted and, depending on the level heterogeneity, determined by the ψ2-based Q test and the Inconsistency Index (I2), fixed-effects or random-effects models were used to calculate pooled odds ratios (ORs) with 95% confidence intervals (95%CIs) for the heterozygous, homozygous, dominant, recessive, and allelic genetic models.

RESULTS

From 708 identified publications, 33 were used in this analysis. For the -174 polymorphism, Asians (ORheterozygous=7.57, 95%CI: 2.28-25.14, ORhomozygous=5.84, 95%CI: 2.06-16.56, ORdominant=7.21, 95%CI: 2.30-22.63, ORrecessive=5.04, 95%CI: 1.78-14.28, ORallelic=6.60, 95%CI: 2.26-19.28, p<.05) and Middle East countries (ORheterozygous=2.30, 95%CI: 1.10-4.81, ORdominant=2.27, 95%CI: 1.22-4.22, ORallelic=2.29, 95%CI: 1.24-4.23, p<.05) were associated with a significant risk of developing RA. Whereas, for Latinos, the C-allele was associated with a benefit (ORhomozygous=0.26, 95%CI: .08-.82, ORrecessive=.25, 95%CI: .08-.80, p<.05). For the -572 polymorphism, Asians demonstrated a significant association for the homozygous and recessive genetic models (8 studies, ORhomozygous=1.56, 95%CI: 1.16-2.09, ORrecessive=1.63, 95%CI: 1.08-2.45, p<.05). For the -597 polymorphism, no association was observed.

CONCLUSIONS

Here, the -174 G>C polymorphism increased the risk of developing RA in Asians and Middle East populations. Interestingly, for Latinos, the polymorphism was associated with a benefit. For the -572 polymorphism, only the Asian population showed an increased risk of developing RA for the CC genotype.

Association between plasma macrophage migration inhibitor factor and deep vein thrombosis in patients with spinal cord injuries

The patients with spinal cord injury (SCI) suffered significantly higher risk of deep vein thrombosis (DVT) than normal population. The aim was to assess the clinical significance of macrophage migration inhibitory factor (MIF) as the risk factor for DVT in acute SCI patients. 207 Chinese patients were enrolled in this study, including thirty-nine (39) patients (18.8 %; 95 %CI: 13.5 %–24.2 %) diagnosed as DVT at the follow-up of 1 month. Nine (9) of the 39 patients (23.1%) were suspected of thrombosis before the screening. The MIF levels in plasma of DVT patients were significantly higher than DVT-free patients. The risks of DVT would be increased by 11 % (OR _unadjusted: 1.11; 95% CI, 1.06–1.17, P<0.001) and 8 % (OR _adjusted: 1.08; 1.03–1.14, P=0.001), for each additional 1 ng/ml of MIF level. Furthermore, after MIF was combined with established risk factors, area under the receiver operating characteristic curve (standard error) was increased from 0.82(0.035) to 0.85(0.030). The results showed the potential association between the high MIF levels in plasma and elevated DVT risk in SCI patients, which may assist on early intervention.

Association between interleukin-1, interleukin-6, and tumor necrosis factor-alpha polymorphisms and juvenile idiopathic arthritis: a meta-analysis

INTRODUCTION

In juvenile idiopathic arthritis (JIA), interleukin (IL)-1, IL-6, and tumor necrosis factor-alpha (TNF-α) are associated with development and progression of JIA. We investigated whether IL-1, IL-6, and TNF-α polymorphisms were associated with susceptibility to JIA.

EVIDENCE ACQUISITION

A meta-analysis was conducted on the associations between IL-1α-899 C/T, IL-1β-511 C/T, IL-6-174 G/C, and TNF-α-308 G/A and -238 G/A polymorphisms, and JIA (PubMed and Embase).

EVIDENCE SYNTHESIS

A total of 27 studies involving 4678 JIA patients and 7634 controls were considered in the meta-analysis. There was no association between the IL-1α-899 C/T, IL-1β-511 C/T, IL-6-174 G/C, and TNF-α-308 G/A and -238 G/A polymorphisms, and JIA in allele contrast or any other genetic models. In subgroup analysis based on subtype, except for the dominant model of TNF-α-238 G/A, systemic JIA was not significantly associated with IL-6 and TNF-α polymorphisms. In Caucasians, the dominant and additive models of IL-1β-511 C/T were significantly associated with JIA (odds ratio [OR] 1.48, 95% confidence interval [CI] 1.09-2.00, P=0.01; OR 1.46, 95% CI 1.05-2.03, P=0.02, respectively).

CONCLUSIONS

This meta-analysis showed no association between IL-1, IL-6, and TNF-α polymorphisms, and JIA, but the TT genotype of IL-1β -511 C/T was associated with higher prevalence of JIA in Caucasians.

Association between interleukin-10 polymorphisms and juvenile idiopathic arthritis: a meta-analysis

INTRODUCTION

The aim of this review is to investigate IL-10 polymorphisms (-1082 G/A, -819 C/T, and -592 C/A) and their association with susceptibility to JIA.

EVIDENCE ACQUISITION

A meta-analysis was conducted after database search for relevant articles (MEDLINE and EMBASE).

EVIDENCE SYNTHESIS

A total of seven studies involving 1495 patients and 1670 controls were considered in the meta-analysis. There was no association between the IL-10 -1082 G/A, -819 C/T, and -592 C/A polymorphisms and JIA in allele contrast and any of the genetic models (allele contrast: odds ratio [OR] 0.90, 95% confidence interval [CI] 0.79-1.02, P=0.09; OR=0.97, 95% CI 0.83-1.13, P=0.68; OR=0.92, 95% CI 0.81-1.06, P=0.24, respectively). In subgroup analysis, none of the subtypes of JIA including systemic, rheumatoid factor (RF)-positive polyarticular, RF-negative polyarticular, and oligoarticular was not significantly associated with IL-10 polymorphism. Meta-analysis of the IL-10 haplotype revealed no association between GCC, ACC, and ATA haplotypes and JIA.

CONCLUSIONS

This meta-analysis showed that IL-10 polymorphisms were not associated with risk of JIA.

Meta-analyses of IL1A polymorphisms and the risk of several autoimmune diseases published in databases

Background

Based on published data, we aimed to quantitatively elucidate the possible genetic influence of rs17561 G/T and rs1800587 C/T polymorphisms of the IL1A (interleukin 1 alpha) gene in the susceptibility to several autoimmune diseases.

Methods

A series of meta-analyses were carried out. After database searching, we utilized our inclusion/exclusion criteria to screen and include the eligible studies. P_association (P value of association test), Bonferroni-corrected P_association value; false discovery rate (FDR)-corrected P_association, ORs (odd ratios), and 95% CI (confidence interval) were generated to assess the magnitudes of genetic relationships.

Results

A total of 35 eligible articles were included. Pooled analysis data of both rs17561 G/T and rs1800587 C/T in the overall population indicated a negative association between cases of autoimmune diseases and negative controls (all P_association>0.05, Bonferroni-corrected P_association>0.05, FDR-corrected P_association>0.05). Similar results were found in most subgroup analyses (all P_association>0.05, Bonferroni-corrected P_association>0.05, FDR-corrected P_association>0.05), apart from the rs1800587 in the Graves’ disease subgroup, which showed an increased risk in some cases, compared with controls, under the models of allele T vs. C, carrier T vs. C, CT+TT vs. CC, and CT vs. CC (all P_association<0.05, Bonferroni-corrected P_association<0.05, FDR-corrected P_association>0.05, OR>1).

Conclusion

Based on the available data, C/T genotype of the rs1800587 polymorphism within IL1A gene may be associated with an increased Graves’ disease risk. We did not see evidence regarding a positive role for rs1800587 or rs17561 in the risk of other autoimmune diseases, such as systemic sclerosis or rheumatoid arthritis. These conclusions still merit further data support and molecular exploration.

Increased serum levels and promoter polymorphisms of macrophage migration inhibitory factor in schizophrenia

BACKGROUND

Numerous studies have suggested that an immune system imbalance plays an important role in schizophrenia. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine. It plays multiple roles in various biological processes, including inflammation and neurogenesis. Furthermore, several exhaustive serum proteomic profiling studies have identified MIF as a potential biomarker of schizophrenia. Here, we investigate MIF protein levels in serum and postmortem prefrontal cortex in patients with schizophrenia and controls. Moreover, we investigate the association of two functional polymorphisms in the MIF gene promoter region (MIF-794CATT_5-8 microsatellite and MIF-173G/C single-nucleotide polymorphism [SNP]) with schizophrenia.

METHODS

We measured serum MIF levels with an enzyme-linked immunosorbent assay (ELISA) (51 patients vs. 86 controls) and postmortem brain MIF levels with a western blotting assay (18 patients vs. 22 controls). Subsequently, we genotyped the MIF-794CATT_5-8 microsatellite with a fluorescence-based fragment assay and the MIF-173G/C SNP with a TaqMan SNP genotyping assay (1483 patients vs. 1454 controls).

RESULTS

Serum MIF levels were significantly higher in patients with schizophrenia than in controls (p=0.00118), and were positively correlated with antipsychotic dose (Spearman's r=0.222, p=0.0402). In addition, an earlier age of onset was observed in patients with a high serum MIF level (≥40ng/mL) than those with a low serum MIF level (<40ng/mL) (p=0.0392). However, postmortem brain MIF levels did not differ between patients with schizophrenia and controls. The association study revealed that the CATT₆-G haplotype was nominally significantly associated with schizophrenia (p=0.0338), and that the CATT₆ allele and CATT₆-G haplotype were significantly associated with female adolescent-onset schizophrenia (AsOS) (corrected p=0.0222 and p=0.0147, respectively).

CONCLUSIONS

These results suggest that serum MIF level is a potential pharmacodynamic and/or monitoring marker of schizophrenia, and is related to a novel antipsychotic effect beyond dopamine antagonism. Furthermore, the MIF gene polymorphisms are associated with the risk for schizophrenia especially in adolescent females, and are potential stratification markers of schizophrenia. Further studies of MIF are warranted to elucidate the pathophysiology of schizophrenia and the effects of antipsychotics.

Interferon regulatory factor signaling in autoimmune disease

Interferon regulatory factors (IRFs) play critical roles in pathogen-induced innate immune responses and the subsequent induction of adaptive immune response. Dysregulation of IRF signaling is therefore thought to contribute to autoimmune disease pathogenesis. Indeed, numerous murine in vivo studies have documented protection from or enhanced susceptibility to particular autoimmune diseases in Irf-deficient mice. What has been lacking, however, is replication of these in vivo observations in primary immune cells from patients with autoimmune disease. These types of studies are essential as the majority of in vivo data support a protective role for IRFs in Irf-deficient mice, yet IRFs are often found to be overexpressed in patient immune cells. A significant body of work is beginning to emerge from both of these areas of study - mouse and human.

Association of interleukin-1 family gene polymorphisms with juvenile idiopathic arthritis in Iranian population

BACKGROUND

Cytokines, including interleukin-1 (IL-1), seem to contribute towards the pathogenesis of juvenile idiopathic arthritis (JIA), so this study was designed to evaluate the associations of IL-1 gene cluster and IL-1 receptor (IL-1R) gene single nucleotide polymorphisms (SNPs) with JIA proneness in Iranian population.

MATERIALS AND METHODS

Genomic DNA of 55 Iranian patients with JIA and 140 controls were extracted and typed for IL-1α gene at position -889, IL-1β gene at positions -511 and +3962, IL-1R gene at position Pst-I 1970, and interleikin-1 receptor antagonist (IL-1Ra) gene at position Mspa-I 11100, using polymerase chain reaction with sequence-specific primers method, and compared between patients and controls.

RESULTS

The CC genotype of IL-1Ra at Mspa-I 11100 position was found to be more frequent in patients with JIA compared to healthy individuals (P=0.03), although the CT genotype at the same position was significantly higher in the control group in comparison with patients with JIA (P=0.02). No significant differences were observed between the two groups of case and control for IL-1α (-889 C/T), IL-1β (-511 C/T and +3962 C/T) and IL-1R (Pst-1 1970 C/T).

CONCLUSION

The results of the present investigation suggest that certain IL-1Ra gene variants are associated with individuals' susceptibility to JIA. Nevertheless, further studies are required to establish the results of the current study.

Association of Interleukin-2, but not Interferon-Gamma, single nucleotide polymorphisms with juvenile idiopathic arthritis

BACKGROUND

Cytokines, including interleukin-2 (IL-2) and interferon-gamma (IFN-γ), seem to play a role in the pathogenesis of juvenile idiopathic arthritis (JIA). The aim of this study was to investigate the associations of IL-2 and IFN-γ single nucleotide polymorphisms (SNPs) with susceptibility to JIA in an Iranian population.

METHODS

Genomic DNA of 54 Iranian patients with JIA and 139 healthy unrelated controls were typed for IL-2 (G/T at -330 and +166) as well as IFN-γ gene (A/T at +874), using polymerase chain reaction with sequence-specific primers method, and compared between patients and controls.

RESULTS

A significantly higher frequency of the IL-2 -330 GG genotype (p<0.01) was found in the JIA patients compared to the controls. However, the GT genotype at the same position was notably lower than in controls (p<0.01). Moreover, IL-2 (-330, +166) GT haplotype was more frequent in patients with JIA in comparison with controls. No significant differences was observed between the two groups of case and control for IL-2 (G/T at +166) and IFN-γ (A/T at +874) SNPs.

CONCLUSION

The results of the current study suggest that certain SNPs of IL-2 gene have association with individuals' susceptibility to JIA. However, further investigations are required to confirm the results of this study.

Polymorphisms of genes encoding interleukin-4 and its receptor in Iranian patients with juvenile idiopathic arthritis

As cytokines, including interleukin-4 (IL-4), seem to have a pivotal role in the pathogenesis of juvenile idiopathic arthritis (JIA), this study is aimed at investigating of association of polymorphisms in IL-4 and IL-4 receptor α (IL-4RA) genes with susceptibility to JIA. A case-control study was conducted on 53 patients with JIA and 139 healthy unrelated controls. Single nucleotide polymorphisms of IL-4 gene at positions -1098, -590, and -33, as well as IL-4RA gene at position +1902 were genotyped using polymerase chain reaction with sequence-specific primers method and compared between patients and healthy individuals. At the allelic level, C allele at IL-4 -33 was found to be more frequent in patients compared to control (P value <0.01). At the genotypic level, CC genotype at IL-4 -590 (P value <0.01), together with CC and TT genotypes at IL-4 -33 (P value <0.01), were significantly higher in patients with JIA, while TC genotypes at IL-4 -590 and -33 positions were found to be lower in case group (P value <0.01). At the haplotypic level, IL-4 (positions -1098, -509, -33) TTC, GCC, and TTT haplotypes were significantly lower than controls (P value <0.01, P value = 0.03, and P value = 0.04, respectively). Although, TCC haplotype at the same positions was found to be higher in patients (P value <0.01). Polymorphic site of +1902 IL-4RA gene did not differ between cases and controls. Polymorphisms in promoter region of IL-4 but not IL-4RA genes confer susceptibility to JIA and may predispose individuals to adaptive immune responses.

The impact of the IL-1β, IL-1Ra, IL-2, IL-6 and IL-10 gene polymorphisms on the development of Behcet's disease and their association with the phenotype

BACKGROUND AND OBJECTIVE

This trial was designed to investigate the effects of the interleukin (IL)-1β, IL-1Ra, IL-2, IL-6, IL-10 gene polymorphisms on Behcet's disease (BD) occurrence and the association between the polymorphisms and the phenotype.

MATERIALS AND METHOD

The study population consisted of 71 patients and 70 age and gender-matched healthy subjects. Each of the participants had 2cc of blood withdrawn, which was placed into a whole blood tube, and the DNA was obtained using the NucleoSpin(®) Blood DNA Isolation kit. To display the band lengths, the products were amplified using the primary pairs of the interleukins investigated and developed in a 2% agarose gel.

RESULTS

There were no significant differences between the groups with respect to the IL-1Ra, IL-1β, IL-2, IL-6 and the IL-10 gene polymorphism distributions. In the patient group the IL-1RN2 gene polymorphism was detected to be statistically correlated with the presence of articular involvement (p=0.0283) and the IL-1β gene polymorphism was statistically correlated with the presence of an ocular lesion (p=0.0178). The evaluation of the IL-2 gene polymorphism (p=0.0065) and IL-10 gene polymorphism (p=0.0483) distributions with respect to age of BD onset revealed a statistically significant distribution.

CONCLUSION

The statistical correlations between the articular involvement and IL-1RN, the ocular involvement and the IL-1β, and the age of disease onset and the IL-2 and IL-10 gene polymorphisms, detected for the first time in the literature, suggest that these polymorphisms could be statistically associated with the disease symptoms and used as prognostic factors.

Ethnic variation in interleukin-6 -174 (g/c) polymorphism in the malaysian population

Interleukin-6 (IL-6) is one of the cytokines that has been well studied and implicated in many diseases including cancers. The frequency of the IL-6 –174 (G/C) polymorphism had been proven to differ in various populations. Malaysia is a country with three major ethnic populations, Malays, Chinese and Indians. In this study, we proposed to determine the G or C allele frequency of the IL-6 –174 polymorphism in these three populations. A total of 348 blood samples were available for analysis. The median age for the subjects was 31 years. There were a total of 245 males and 103 females. A total of 86 Malays (25.0%), 122 Chinese (33.0%) and 140 Indians (40.0%) were genotyped. The result showed a significant difference in the G or C allele frequency of the –174 polymorphism. The total frequencies for the G and C alleles were 91.0 and 9.0%, respectively. In the Malays, the allele frequency of the C allele was 4.0% compared with 19.0% in the Indians. The C allele was not detected in the Chinese population. This finding is the first reported on the Malaysian population and may be important in determining risk of diseases associated with the IL-6 polymorphism in these three populations.

Effect of IL-12B, IL-2, TGF-β1, and IL-4 polymorphism and expression on hepatitis B progression

The hepatitis B virus (HBV) infection-induced chronic inflammation is considered to be the major etiological factor for HBV-related disease chronicity. Cytokines act as the key coordinators of the inflammatory responses involved in HBV disease pathogenesis. The present study assessed association among IL-12B(+1188), IL-2(-330), TGF-β1(-509), and IL-4(-590) genotypes; mRNA; and protein levels with HBV-hepatocellular carcinoma (HCC) risk in India. For this, 403 subjects (153 controls, 67 inactive HBV-carriers, 62 chronic-active HBV patients, 62 HBV-cirrhotics, and 59 HBV-HCC ssubjects) were enrolled in the study. The genotyping was carried by polymerase chain reaction (PCR)-restriction fragment length polymorphism (IL-12+1188A/C, IL-2-330T/G, and TGF-β1-509C/T), and allele specific (AS)-polymerase chain reaction (IL-4-590C/T). Enzyme-linked immunosorbent assay and reverse transcriptase-polymerase chain reaction methods were used for assessing protein and the mRNA expression, respectively, of the mentioned cytokines. The study revealed that the IL-12B(+1188) CC genotype shared a significant positive association with hepatitis, among controls. While, in the case of IL-2(-330), both the TG and GG genotypes were not significantly associated with HCC risk. The TGF-β1(-509) TT genotype acted as a potential protective factor for cirrhosis and the HCC risk, among carriers. On the contrary, the IL-4(-590) CT genotype was found to be a vital protective factor for the development of hepatitis, among carriers. Besides, IL-12B, TGF-β1, and IL-2 seem to be majorly involved in the development of HCC, while, IL-4 might be responsible for the progression of the HBV disease till cirrhosis development. These initial findings are indicative of the vital role of genotypes and/or levels of IL-12B, IL-2, IL-4, and TGF-β1 in HBV disease chronicity in Indian population.

TNF-α Polymorphisms in Juvenile Idiopathic Arthritis: Which Potential Clinical Implications?

Whether tumor necrosis factor alpha (TNF-α) gene polymorphisms (SNPs) influence disease susceptibility and treatment of patients with juvenile idiopathic arthritis (JIA) is presently uncertain. TNF-α is one of the most important cytokine involved in JIA pathogenesis. Several single nucleotide polymorphisms (SNPs) have been identified within the region of the TNF-α gene but only a very small minority have proven functional consequences and have been associated with susceptibility to JIA. An association between some TNF-α SNPs and adult rheumatoid arthritis (RA) susceptibility, severity and clinical response to anti-TNF-α treatment has been reported. The most frenquetly studied TNF-α SNP is located at -308 position, where a substitution of the G allele with the rare A allele has been found. The presence of the allele -308A is associated to JIA and to a poor prognosis. Besides, the -308G genotype has been associated with a better response to anti-TNF-α therapy in JIA patients, confirming adult data. Psoriatic and oligoarticular arthritis are significantly associated to the -238 SNP only in some works. Studies considering other SNPs are conflicting and inconclusive. Large scale studies are required to define the contribution of TNF-α gene products to disease pathogenesis and anti-TNF-α therapeutic efficacy in JIA.

Genome-wide association analysis of juvenile idiopathic arthritis identifies a new susceptibility locus at chromosomal region 3q13

OBJECTIVE

In a genome-wide association study of Caucasian patients with juvenile idiopathic arthritis (JIA), we have previously described findings limited to autoimmunity loci shared by JIA and other diseases. The present study was undertaken to identify novel JIA-predisposing loci using genome-wide approaches.

METHODS

The discovery cohort consisted of Caucasian JIA cases (n = 814) and local controls (n = 658) genotyped on the Affymetrix Genome-Wide SNP 6.0 Array, along with 2,400 out-of-study controls. In a replication study, we genotyped 10 single-nucleotide polymorphisms (SNPs) in 1,744 cases and 7,010 controls from the US and Europe.

RESULTS

Analysis within the discovery cohort provided evidence of associations at 3q13 within C3orf1 and near CD80 (rs4688011) (odds ratio [OR] 1.37, P = 1.88 × 10(-6) ) and at 10q21 near JMJD1C (rs647989 [OR 1.59, P = 6.1 × 10(-8) ], rs12411988 [OR 1.57, P = 1.16 × 10(-7) ], and rs10995450 [OR 1.31, P = 6.74 × 10(-5) ]). Meta-analysis provided further evidence of association for these 4 SNPs (P = 3.6 × 10(-7) for rs4688011, P = 4.33 × 10(-5) for rs6479891, P = 2.71 × 10(-5) for rs12411988, and P = 5.39 × 10(-5) for rs10995450). Gene expression data on 68 JIA cases and 23 local controls showed cis expression quantitative trait locus associations for C3orf1 SNP rs4688011 (P = 0.024 or P = 0.034, depending on the probe set) and JMJD1C SNPs rs6479891 and rs12411988 (P = 0.01 or P = 0.04, depending on the probe set and P = 0.008, respectively). Using a variance component liability model, it was estimated that common SNP variation accounts for approximately one-third of JIA susceptibility.

CONCLUSION

Genetic association results and correlated gene expression findings provide evidence of JIA association at 3q13 and suggest novel genes as plausible candidates in disease pathology.

IL1 gene polymorphisms in enthesitis related arthritis category of juvenile idiopathic arthritis (ERA-JIA)

Cytokine gene loci are one of the potential susceptibility factors in immuno-inflammatory diseases. Interleukin1 (IL-1) is a major monocyte derived proinflammatory cytokine that mediates tissue damage and cartilage loss in chronic arthritis. IL-1 locus has been linked to various autoimmune diseases, but data on juvenile idiopathic arthritis (JIA) is limited. Ninety-four patients with enthesitis related arthritis (ERA) category of JIA (ILAR criteria) were included in the study. One hundred eighty-five healthy blood donors were used as controls. IL-1Ra VNTR polymorphism was done by PCR using specific primers, and allele assignment was done on product size obtained on 2% agarose gel. IL-1α-889 and IL-β-511 polymorphism was done using PCR-RFLP method. Among 94 patients, 87 were males, and the mean age at onset of disease was 11.8 + 1.8 years; 17 had history of uveitis, and 13 had positive family history. Forty-two had enthesitis, and 51 had inflammatory back pain; all had arthritis. Seventy-six were HLA B27 positive. All three loci genotypes were in the Hardy-Weinberg equilibrium in controls. There was no difference in genotype frequency among patients and controls for IL-1Ra, IL-1α-889 and IL-β-511. IL1*RN2 homozygosity was more common in patients, whereas carriage rate for IL1*RN1 was less frequent in patients. Haplotype frequencies were also similar in both groups. IL-1 gene cluster is not a susceptibility locus for ERA.

Maternal interleukin-6 (-174) C/C polymorphism is associated with chorioamnionitis and cystic periventricular leucomalacia of the preterm infant

OBJECTIVE

To evaluate the association between maternal interleukin (IL)-6 G(-174)C polymorphism and cystic periventricular leukomalacia (cPVL) of the preterm newborn.

STUDY DESIGN

After searching a local database, we recruited 132 preterm infants with diagnosis of cPVL, 44 Caucasian mothers were also recruited to participate in this candidate gene-association study at a single teritary care center. Data related to maternal IL-6 G(-174)C polymorphisms were compared with 41 controls, and furthermore compared with data from umbilical cord blood samples from a consecutive birth cohort of 395 healthy newborns, and published data from Caucasian populations including 1104 adults, respectively. In addition, subgroup analysis was performed in cases with either history of preterm premature rupture of the membranes (PPROM) or clinical chorioamnionitis (CCA). IL-6 genotyping was performed using an allele-specific polymerase chain reaction technique.

RESULT

Frequencies of the IL-6 G(-174)C polymorphisms did not differ between cases (GG, 29.5%; GC, 54.5% and CC, 15.9%) and controls (GG, 34.2; GC, 51.2 and CC, 14.6%). Subgroup analysis of 31 cases with history of PPROM (GG, 25.8; GC, 54.8 and CC 19.4%) and controls did not reveal significant differences, but a significantly higher frequency of the CC genotype was found in 23 cases with a history of CCA (34.8%) compared with controls by either univariate (P=0.032; odds ratio 3.11, 95% confidence interval (CI) 1.11 to 8.68) or multivariate analysis (P=0.049, odds ratio 2.54, 95% CI 1.01 to 6.45). These data were confirmed by a comparing the CC genotype frequency to 395 term controls (CC 14.7%, P=0.005) and to the mean CC genotype frequency of 1104 Caucasian adults (CC 15.6%, P<0.0001).

CONCLUSION

Frequencies of the IL-6 G(-174)C polymorphisms did not differ between groups. Subgroup analysis revealed an association of the CC genotype with CCA and cPVL in the preterm newborn.

Genetic associations in type I interferon related pathways with autoimmunity

Type I interferons play an outstanding role in innate and adaptive immunity by enhancing functions of dendritic cells, inducing differentiation of monocytes, promoting immunoglobulin class switching in B cells and stimulating effector functions of T cells. The increased production of IFNα/β by plasmacytoid dendritic cells could be responsible for not only efficient antiviral defence, but it also may be a pathological factor in the development of various autoimmune disorders. The first evidence of a genetic link between type I interferons and autoimmune diseases was the observation that elevated IFNα activity is frequently detected in the sera of patients with systemic lupus erythematosus, and that this trait shows high heritability and familial aggregation in their first-degree healthy relatives. To date, a number of genes involved in interferon signalling have been associated with various autoimmune diseases. Patients with systemic lupus erythematosus, Sjögren's syndrome, dermatomyositis, psoriasis, and a fraction of patients with rheumatoid arthritis display a specific expression pattern of interferon-dependent genes in their leukocytes, termed the interferon signature. Here, in an attempt to understand the role of type I interferons in the pathogenesis of autoimmunity, we review the recent advances in the genetics of autoimmune diseases focusing on the association of genes involved in type I interferon pathways.

Susceptibility to JRA/JIA: complementing general autoimmune and arthritis traits

Juvenile rheumatoid arthritis (JRA), also known as juvenile idiopathic arthritis (JIA), includes the most common chronic autoimmune arthropathies of childhood. These two nomenclatures for classification include components representing the major subclasses of disease. The chromosomal regions and the genes involved in these complex genetic traits are being elucidated, with findings often specific for a particular disease subtype. With the advent of new SNP technologies, progress is being made at an ever-increasing pace. This review discusses the difficulties of deciphering the genetic components in complex disorders, while demonstrating the similarities that JRA shares with other autoimmune disorders. Particular emphasis has been placed on positive findings either for candidate genes that have been replicated independently in JRA/JIA, or findings in JRA for which consistent results have been reported in other forms of autoimmunity.

Tumor Necrosis Factor-α −308 Genotypes Influence Inflammatory Activity and TNF-α Serum Concentrations in Children with Juvenile Idiopathic Arthritis

Objective.

Considering the relevance of tumor necrosis factor-α (TNF-α) in the pathophysiology of juvenile idiopathic arthritis (JIA), it is likely that polymorphisms in its promoter area may be relevant in disease susceptibility and activity. We investigated if clinical measures of JIA activity and TNF-α serum concentrations were associated with TNF-α −308 genotypes.

Methods.

Portuguese patients with JIA in 5 pediatric rheumatology centers were recruited consecutively, along with a control group of healthy subjects. Demographic and clinical data and blood samples were collected from each patient. DNA was extracted for analysis of TNF-α gene promoter polymorphisms at position −308 by restriction fragment-length polymorphism.

Results.

One hundred fourteen patients and 117 controls were evaluated; 57% of patients presented the oligoarticular subtype, 25% the polyarticular subtype, 8% the systemic subtype, and 9% had enthesitis-related arthritis and 5% psoriatic arthritis. Twenty-four percent of the patients presented the −308 GA/AA genotypes and 76% the −308 GG genotype, similar to findings in controls. Patients with the −308 GA/AA genotype had higher degree of functional impairment, erythrocyte sedimentation rate, 100-mm visual analog scale score for disease activity, and TNF-α levels compared to those with the −308 GG genotype.

Conclusion.

TNF-α −308 GA/AA genotypes were found to be related to higher inflammatory activity and worse measures of disease activity in Portuguese patients with JIA. They were not associated with susceptibility to JIA.

A comprehensive review of the genetics of juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic arthropathy of childhood which is believed to be influenced by both genetic and environmental factors. The progress in identifying genes underlying JIA susceptibility using candidate gene association studies has been slow. Several associations between JIA and variants in the genes encoding the human leukocyte antigens (HLA) have been confirmed and replicated in independent cohorts. However it is clear that genetic variants outside the HLA also influence susceptibility to JIA. While a large number of non-HLA candidate genes have been tested for associations, only a handful of reported associations such as PTPN22 have been validated. In this review we discuss the principles behind genetic studies of complex traits like JIA, and comprehensively catalogue non-HLA candidate-gene association studies performed in JIA to date and review several validated associations. Most candidate gene studies are underpowered and do not detect associations, and those that do are often not replicated. We also discuss the principles behind genome-wide association studies and discuss possible implications for identifying genes underlying JIA. Finally we discuss several genetic variants underlying multiple clinically distinct autoimmune phenotypes.

Associations between interferon regulatory factor–1 polymorphisms and Behçet’s disease

Interferon regulatory factor-1 (IRF-1) is a transcription factor that regulates the functions of type I and II interferons and plays a role in host protection. Behçet's disease (BD) is an idiopathic systemic vasculitis that is often complicated with thrombotic features, and infectious agents have long been postulated to be a disease-triggering factor in its pathogenesis. The authors investigated the distributions of IRF-1 promoter -415 C/A, -410 A/G, and -300 A/G, and 3'-untranslated region (UTR) A/G polymorphisms in 105 BD patients (mean age 41.7 +/- SEM 1.1 years, 44 male and 61 female) and in 105 gender- and age-matched healthy controls. The frequencies of individual alleles and genotypes were not different between the control and BD groups. However, the frequency of AGGG haplotype was significantly higher (73.5% vs 60.2%, odds ratio [OR] = 1.842, 95% confidence interval [95% CI] = 1.219-2.783, p(c) = 0.036) and that of the CAAG haplotype was significantly lower (2.2% vs 9.5%, OR = 0.195, 95% CI = 0.068-0.559, p(c) = 0.02) in BD patients than in healthy controls. In addition, the frequency of the AGGG haplotype was significantly higher (80.3% vs 57.4%, OR = 3.033, 95% CI = 1.716-5.360, p(c) = 0.001) and that of the CAAG haplotype was significantly lower (0.8% vs 12.3%; OR = 0.059, 95% CI = 0.010-0.357, p(c) = 0.005) in female BD patients than female controls. By subgroup analyses, the CAAA haplotype tended to be more common in BD patients with moderate or severe disease than in those with mild disease (25.4% vs 13.6%, OR = 2.158, 95% CI = 1.046-4.440, p = 0.037 before Bonferroni correction). When BD patients were subclassified by a history of deep vein thrombosis (DVT), the CAAA haplotype was found to be significantly increased the risk of DVT (42.1% vs 15.7%, OR = 3.906, 95% CI = 1.836-8.324, p(c) = 0.0015) and the AGGG haplotype tended to reduce this risk (57.9% vs 77.3%, OR = 0.403, 95% CI = 0.195-0.834, p(c) = 0.0685). Furthermore, the frequency of the CAAA haplotype was significantly higher in BD patients that had experienced a thrombotic event than in those that had not (40.5% vs 15.5%, OR = 3.7147, 95% CI = 1.778-7.770, p(c) = 0.0015). These results suggest that IRF-1 is a novel susceptibility gene in BD, especially in women, and furthermore, that IRF-1 polymorphisms may be related to thrombosis in BD patients.

No evidence for genetic association of interferon regulatory factor 1 in juvenile idiopathic arthritis

OBJECTIVE

Juvenile idiopathic arthritis (JIA) comprises several clinically distinct subgroups and is the most widespread cause of chronic childhood disability. A significant association between JIA and a polymorphism in the interferon regulatory factor 1 (IRF-1) gene has previously been reported, implicating IRF1 in disease susceptibility. The aim of this study was to replicate the IRF1 association in JIA using single-marker and haplotype analyses in a case-control study, using control subjects different from those in the previous study and a larger cohort of patients (n = 765).

METHODS

DNA from 765 patients with JIA and 508 unaffected control subjects was genotyped for 4 single-nucleotide polymorphisms in the IRF-1 gene. Association of genotypes at the IRF1 loci was assessed using single-marker and haplotype analyses.

RESULTS

No significant differences in genotype frequency or allele frequency were observed between patients and control subjects.

CONCLUSION

This replication study used a much larger patient cohort to examine the association of IRF1 in JIA. However, despite the increased statistical power, we observed no significant association for IRF1 markers, either individually or as haplotypes. It is therefore unlikely that this gene is involved in JIA susceptibility.

IL1 and TNF gene polymorphisms in patients with juvenile idiopathic arthritis treated with TNF inhibitors

OBJECTIVE

To investigate the genetic contribution of cytokine gene polymorphisms (interleukin 1 (IL1) and tumour necrosis factor alpha (TNFalpha)) on disease phenotype and on response to TNF-blocking agents in a population of patients with juvenile idiopathic arthritis (JIA).

METHODS

A cohort of 107 consecutive patients with JIA who were receiving treatment with anti-TNF agents was enrolled in this study. Analysis of genetic polymorphisms for IL1B +3954, IL1RA +2018, TNFalpha -238 and TNFalpha -308 was performed by enzyme-linked oligo sorbent assay, and compared with those obtained from 630 healthy Caucasians and 263 adult patients with rheumatoid arthritis. Relevant demographic, clinical and laboratory data were collected from clinical charts and entered into a customised database, and chi(2) analysis was performed to compare cytokine polymorphisms with disease type according to the International League of Associations for Rheumatology criteria, presence of uveitis, rheumatoid factor and anti-nuclear antibody positivity, erosive disease, frequency of adverse effects to anti-TNF and clinical response after 3 months.

RESULTS

The T/T genotype of the IL1B +3954 polymorphism was absent in patients with JIA and present in 5% of controls (p = 0.015). No significant correlation was found between the studied polymorphisms and clinical or laboratory variables considered. Clinical response to TNF inhibitors at 3 months was not associated with the genetic polymorphisms considered.

CONCLUSION

In our cohort, the absence of the rare IL1B +3954 gene polymorphism was associated with JIA, but without specificity to particular disease phenotypes. The TNF and IL1 gene polymorphism studied did not seem to be associated with response to anti-TNF treatment.

Polymorphisms in the interleukin-4 and IL-4 receptor genes modify risk for chronic inflammatory arthropathies in women

Rheumatoid and juvenile idiopathic arthritis (RA, JIA) are chronic inflammatory arthropathies with polygenic autoimmune background. We analysed the IL-4 +33 C/T and IL-4R Q551R single nucleotide polymorphisms (SNPs) in 294 RA, 72 JIA and 165 controls from Northern Ireland. Analysis of the individual phenotypes (RA or JIA) showed that both the IL-4 +33 TT (P = 0.02; OR: 0.25, 95% CI: 0.07-0.87) and the IL-4R Q551R CC genotypes (P = 0.001; OR: 0.19, 95% CI: 0.06-0.56) were exclusively decreased in female RA patients compared to female controls. Similar non-significant trends were observed in female JIA patients (OR: 0.25, 95% CI: 0.03-2.11 and OR: 0.31, 95% CI: 0.07-1.47, respectively). Analysis of the common phenotype (inflammatory arthropathy; i.e. JIA and RA combined) corroborated the unique association of these polymorphisms with female inflammatory arthropathy (P = 0.013 and 0.002, respectively). This is the first demonstration of sex-specific association of the two foremost genes of the IL-4 signalling cascade with chronic inflammatory arthropathies.

Association of cytokine gene polymorphisms and the release of cytokines from peripheral blood mononuclear cells treated with methotrexate and dexamethasone

Immunosuppressive drugs are widely used in the therapy of autoimmune disorders to suppress autoreactive T cells. The immune system is regulated by the release of cytokines. Cytokine are potent immunomodulatory molecules that act as mediators of inflammation and the immune response. Primarily secreted by T cell and macrophages, they influence cellular activation, differentiation, and function. Cytokine production is under genetic control. This is evidenced by the identification of polymorphism in cytokine gene regulatory regions that correlate with intra-individual variations in actual cytokine production. The aim of the study was to examine whether the individual differences in the polymorphic cytokine genes can lead to individual variation in release of cytokines after treatment with methotrexate and glucocorticosteroids. The study was carried out on mononuclear cells isolated from peripheral blood of 72 healthy subjects. The cells were activated with PHA and incubated with increasing concentrations of methotrexate (0.1-10 microM) and dexamethasone (0.01-1 microM). Levels of IL-2, IL-4, IL-6, IL-10, and TNFalpha in the culture supernatants were quantified by flow-cytometry using Th1/Th2 kit and correlated with cytokine gene polymorphisms. The increased concentrations of DEX resulted in comparable cytokine concentrations in cultures from subjects with low and high cytokine genotypes. Despite MTX treatment, the cytokine levels were significantly increased in individuals homozygous for the high producer allele. These results suggest that the cytokine gene variants may influence the efficacy of therapy with some immunosuppressive and anti-inflammatory drugs.

Tapasin gene polymorphism in systemic onset juvenile rheumatoid arthritis: a family-based case-control study

Juvenile rheumatoid arthritis (JRA) comprises a group of chronic systemic inflammatory disorders that primarily affect joints and can cause long-term disability. JRA is likely to be a complex genetic trait, or a series of such traits, with both genetic and environmental factors contributing to the risk for developing the disease and to its progression. The HLA region on the short arm of chromosome 6 has been intensively evaluated for genetic contributors to JRA, and multiple associations, and more recently linkage, has been detected. Other genes involved in innate and acquired immunity also map to near the HLA cluster on 6p, and it is possible that variation within these genes also confers risk for developing JRA. We examined the TPSN gene, which encodes tapasin, an endoplasmic reticulum chaperone that is involved in antigen processing, to elucidate its involvement, if any, in JRA. We employed both a case-control approach and the transmission disequilibrium test, and found linkage and association between the TPSN allele (Arg260) and the systemic onset subtype of JRA. Two independent JRA cohorts were used, one recruited from the Rheumatology Clinic at Cincinnati Children's Hospital Medical Center (82 simplex families) and one collected by the British Paediatric Rheumatology Group in London, England (74 simplex families). The transmission disequilibrium test for these cohorts combined was statistically significant (chi2 = 4.2, one degree of freedom; P = 0.04). Linkage disequilibrium testing between the HLA alleles that are known to be associated with systemic onset JRA did not reveal linkage disequilibrium with the Arg260 allele, either in the Cincinnati systemic onset JRA cohort or in 113 Caucasian healthy individuals. These results suggest that there is a weak association between systemic onset JRA and the TPSN polymorphism, possibly due to linkage disequilibrium with an as yet unknown susceptibility allele in the centromeric part of chromosome 6.

Epidemiology of the rheumatic diseases of childhood

Epidemiologic studies of pediatric rheumatologic disease are becoming increasingly focused on subfields of epidemiology. Genetic epidemiology is assuming an ever-greater role in the understanding of disease risks and pathogenesis. Such studies involve major histocompatibility complex, cytokine gene polymorphisms, T cell studies, and microarray-based expression technology. Clinical epidemiology, the study of occurrence and outcomes, increasingly relies on multicenter studies with data improving as study parameters become more standardized. With multicenter studies, there is an increasing trend to study ethnic differences in rheumatologic diseases of children.

IL12B and IRF1 gene polymorphisms and susceptibility to celiac disease

Celiac disease (CD) is a common gastro-intestinal disorder resulting from permanent intolerance to wheat gliadins and related proteins in rye and barley. In addition to the strong genetic association with HLA-DQ2 and HLA-DQ8, a genetic region on chromosomes 5 (CELIAC2) has been identified that harbours a susceptibility gene for CD. The gene(s) responsible for this association, however, remains to be identified. In the present study we evaluated polymorphisms in the genes encoding interleukin-12 p40 (IL12B) and interferon regulatory factor 1 (IRF1). Both genes are located in the celiac2 region, and have key roles in inducing interferon (IFN)-gamma secreting T helper 1 (Th1) cells, one of the immunological hallmarks of CD. The frequencies of a TaqI gene polymorphism in the 3' UTR of IL12B and a HinfI gene polymorphism in the 3' UTR of IRF1 were studied in 258 Dutch CD patients and 237 ethnically matched healthy controls. The transmission of the polymorphic variants from parents to affected child was determined in 123 families with at least one affected child. The frequencies of the IL12B TaqI gene polymorphism and the IRF1 HinfI gene polymorphism did not differ significantly between patients and controls. In addition, in the family study, no deviation from the expected transmission from parents to affected child of any of the polymorphic variants was found. The IL12B TaqI and the IRF1 HinfI gene polymorphisms do not appear to be involved in susceptibility to CD. Further studies on the factors that drive the Th1 immunopathology in CD are required.

The -174G allele of the interleukin-6 gene confers susceptibility to systemic arthritis in children: a multicenter study using simplex and multiplex juvenile idiopathic arthritis families

OBJECTIVE

Levels of interleukin-6 (IL-6) have been shown to correlate with the fever and disease activity of systemic juvenile idiopathic arthritis (JIA). In a previous case-control study, a significant association between the IL-6 -174 nucleotide variant and systemic JIA was noted, and HeLa cell transfection assays show functional differences in levels of transcription of the IL-6 -174 alleles. The present study was undertaken to confirm the previous findings and to assess possible association with variations of the A(n)T(n) tract in the promoter.

METHODS

We studied a cohort of JIA families from 3 countries, using transmission disequilibrium testing. Genotyping of the -174 nucleotide variant was done by restriction fragment length polymorphism, heteroduplex analysis, or allelic discrimination. The A(n)T(n) tract at -392 to -373 was typed using DNA sequencing. Statistical analysis was performed using the programs Transmit and EHplus.

RESULTS

There was a significant excess transmission of the -174G allele in the systemic JIA families (P = 0.041). The excess transmission was only to systemic JIA patients with age at onset >5 years (P = 0.007). No significant association with the other subtypes was found. No A(n)T(n) alleles or -174/A(n)T(n) haplotypes were significantly associated with systemic JIA.

CONCLUSION

This study confirms that the IL-6 -174 nucleotide variant is significantly associated with systemic JIA. The significant excess transmission to patients with age at onset >5 years but not to those with age at onset < or =5 years suggests that there may be genetic heterogeneity between the 2 groups.

Cell-type and donor-specific transcriptional responses to interferon-alpha. Use of customized gene arrays

A sensitive, specific, reproducible, robust, and cost-effective customized cDNA array system based on established nylon membrane technology has been developed for convenient multisample expression profiling for several hundred genes of choice. The genes represented are easily adjusted (depending on the availability of corresponding cDNAs) and the method is accordingly readily applicable to a wide variety of systems. Here we have focused on the expression profiles for interferon-alpha2a, the most widely used interferon for the treatment of viral hepatitis and malignancies, in primary cells (peripheral blood mononuclear cells, T cells, and dendritic cells) and cell lines (Kit255, HT1080, HepG2, and HuH7). Of 150 genes studied, only six were consistently induced in all cell types and donors, whereas 74 genes were induced in at least one cell type. IRF-7 was identified as the only gene exclusively induced in the hematopoietic cells. No gene was exclusively induced in the nonhematopoietic cell lines. In T cells 12, and in dendritic cells, 25 genes were induced in all donors whereas 45 and 42 genes, respectively, were induced in at least one donor. The data suggest that signaling through IFN-alpha2 can be substantially modulated to yield significant cell-type and donor-specific qualitative and quantitative differences in gene expression in response to this cytokine under highly standardized conditions.

Cytokines and juvenile idiopathic arthritis

Cytokines are a large group of polypeptides and small proteins that are effector molecules for cells involved in immune and inflammatory responses. There are agonists and antagonists that interact with each other to maintain a dynamic equilibrium, and ensure eventual recovery of any perturbation, for example, by trauma or infection, of the network toward inflammation. The imbalance between pro- and anti-inflammatory cytokines and the T helper cell subtypes is considered important in the pathogenesis of autoimmune diseases, including juvenile idiopathic arthritis. The measurement of cytokines and chemotactic cytokines in body fluids and synovial tissue has provided insight into the type of immune and inflammatory reaction and the possible presence or absence of regulation. Differences between subtypes of juvenile idiopathic arthritis have been identified with these measurements. But cytokine measurements in serum are not useful for diagnostic purposes, because of the variability during 24 hours, the collection and assay methods, as well as the ease of degradation for most cytokines. The recent interest in the genetic polymorphisms of cytokine genes and their association with juvenile idiopathic arthritis has provided association with a number of cytokine alleles. Confirmation of linkage with disease is only available for tumor necrosis factor and interleukin-6 at present. These genetic variants may be the basis of genetic susceptibility to the persistent imbalance in the inflammatory and immune networks, and determine the phenotype and severity of disease.

Allele frequencies of polymorphisms of TNFA, IL-6, IL-10 and IFNG in an Italian Caucasian population

Polymorphisms in the regulatory and intronic regions of several cytokines have been associated with differential cytokine production. In this paper we genotyped, using the polymerase chain reaction-sequence-specific primers (PCR-SSP) method, a series of 363 healthy Italian Caucasians with the aim of obtaining a reference population for further studies on the role of cytokines in the inflammatory and immune responses. We also compared the results to those for other populations. The polymorphisms analysed were those of tumour necrosis factor alpha (TNFA), interleukin 6 (IL-6), interleukin 10 (IL-10) and interferon gamma (IFNG). We found that the frequency of allele TNFA*1 at position -380 was 87.7% and that of TNFA*2 was 12.4%, significantly different from those of the UK and Japanese populations but not different from that of a population in Gambia. For IL-10 the frequencies of alleles -1082A and -1082G were 63.0% and 37.0% and those of alleles -819C, - 819T, -592C and -592A were 70.8, 29.2, 70.8 and 29.2%, respectively, significantly different from those observed in south-east England, in Manchester and in an Oriental population from southern China. The frequencies of IL-6 alleles - 174C and -174G were 29.0 and 71.0%, respectively; for IFNG polymorphisms at position -874, in the population under evaluation, the alleles -874T and -874A were present in 44.7 and 55.3% of the subjects, respectively. Genotype frequencies of IL-6 were significantly different from those observed in populations from Germany and from the UK. The analysis carried out by our group indicates that there is heterogeneity in the frequencies of the cytokine polymorphisms among the different Caucasian populations, and this underlines the importance of a 'local' reference population when evaluating the clinical relevance of cytokine gene polymorphisms.

Juvenile idiopathic arthritis genetics - what's new? What's next?

Studies have established the magnitude of the genetic basis of juvenile idiopathic arthritis (JIA). JIA is a complex genetic condition and the genes that influence susceptibility are actively being sought. A candidate gene approach is being used by several groups. MHC-, cytokine- and T-cell-related genes have all been positively associated with JIA. Here we review some of the latest genetic data, and discuss ways in which JIA genetic research might proceed.