Rheumatoid arthritis susceptibility and interleukin 10: a study of two ethnically diverse populations

Is macrophage polarization important in rheumatoid arthritis?

Macrophages are myeloid immune cells which are strategically positioned throughout the body, where they engulf and degrade debris, dead cells, and foreign substances, and coordinating the inflammatory processes. Macrophages can be divided into two extreme subsets, classical activation (M1), and alternatively activation (M2). The symptoms and signs of rheumatoid arthritis (RA) would exacerbate with the increase in pro-inflammatory cytokines, whereas anti-inflammatory cytokines will alleviate the symptoms and signs of RA. This review, mainly discusses the effects of Notch, JNK and ERK signaling pathways on the regulation of macrophage polarization, and the effects of pro-inflammatory factors and/or anti-inflammatory cytokines produced by polarized macrophages in RA. Also, we will make an attempt to find out the importance of macrophage polarization in RA treatment as a drug target.

Association of IL-10 gene polymorphisms and susceptibility to Juvenile Idiopathic Arthritis in Egyptian children and adolescents: a case-control study

Background

Juvenile Idiopathic Arthritis (JIA) is the most common chronic arthritis in children worldwide. Among anti-inflammatory cytokines, interleukin-10 (IL-10) is a key immunosuppressive cytokine involved in the pathogenesis of JIA. To date, only a few studies concerned the association of interleukin-10 gene polymorphisms with JIA. In this study, we aimed to investigate 3 cytokine single-nucleotide polymorphisms situated at positions -1082(G/A), −819(C/T), and −592(C/A) in the promoter region of the IL-10 gene to determine whether this polymorphism could be a marker of susceptibility to JIA in Egyptian children and adolescents. We also measured the serum level of IL-10 to assess its relation to such polymorphism.

Methods

This was a case-control study included 100 patients diagnosed with JIA, and matched with age, gender, ethnicity 100 healthy control subjects.

Interleukin-10 −1082(G/A), −819(C/T), and −592(C/A) polymorphisms were genotyped by amplification refractory mutation system- polymerase chain reaction (ARMS)-PCR methodology, while the serum IL10 levels were measured by ELISA method.

Results

Compared to the controls subjects, the frequency of IL-10- AA genotype and A allele at the –1082 position were overrepresented in patients with JIA (OR = 2.7; 95% CI: 1.1–6.4 for the AA genotype; P <0.05 and OR: 1.5; 95% CI: 1.03–2.3 for the A allele; P <0.05 respectively). On the other hand, no significant differences were found between the 2 groups in the genotype or allele frequencies for the –819 and –592 positions. Of note, we found a significant positive association between the IL-10 (-1082) AA genotype and susceptibility to polyarticular JIA (OR: 4.3; 95% CI: 1.5–12.7; P <0.01). We observed that patients with the IL-10 (-1082) AA genotype had significantly lower serum IL-10 levels (2.3 ± 0.9 pg/ml) compared to those with AG genotype (7.6 ± 1.5 pg/ml) and GG genotype (9.5 ± 1.2 pg/ml); P < 0.01, respectively.

Conclusion

We demonstrate for the first time, to the best of our knowledge, that the presence of an A allele or AA gene variant at the –1082 position of the promoter region of the interleukin-10 gene may constitute risk factors for developing JIA in Egyptian children and adolescents. Moreover, we observed a significant positive association between the IL10 –1082 AA gene variant and susceptibility to polyarticular JIA.

Association of single nucleotide polymorphisms in the IL27 gene with rheumatoid arthritis

Rheumatoid arthritis (RA) is one of the autoimmune diseases, where different polymorphisms in cytokine genes play a pathogenic role. Interleukin 27 (IL-27) is a novel pro-/anti-inflammatory cytokine, an excellent candidate for chronic inflammatory disease studies. The aim of the study was to identify polymorphisms in the IL-27 gene and their possible association with susceptibility to and severity of RA. Two hundred and seventy-four patients with RA and of 295 healthy individuals were examined for -924A/G and 4730T/C IL27 gene polymorphisms using PCR-RFLP method and TaqMan SNP genotyping assay, respectively. Haplotype frequencies of IL-27 polymorphisms were estimated using SHEsis platform. Frequencies of the -924GG genotype and the -924G allele were statistically higher in RA patients comparing with the healthy control group (P = 0.008 and P = 0.004, respectively). Overall, strong LD was observed between the IL27 gene -924A/G and 4730 T/C polymorphisms (D' = 0.613, r2 = 0.199). From four possible haplotypes, frequencies of two (CA and CG) showed significant differences between both examined groups (respectively: P < 0.001 and P = 0.001062). The genotype-phenotype analysis showed significant association between the IL-27 4730 T/C polymorphism and HAQ score and means value of the ESR, additionally they revealed that individuals with the polymorphic allele -924G had more advanced disease than wild-type allele carriers. Present findings indicated that IL27 -924A/G polymorphism may be involved in susceptibility to RA in the Polish population.

A(2A) adenosine receptors are differentially modulated by pharmacological treatments in rheumatoid arthritis patients and their stimulation ameliorates adjuvant-induced arthritis in rats

A_2A adenosine receptors (ARs) play a key role in the inhibition of the inflammatory process. The purpose of this study was to evaluate the modulation of A_2AARs in rheumatoid arthritis (RA) patients after different pharmacological treatments and to investigate the effect of A_2AAR stimulation in a rat model of arthritis. We investigated A_2AAR density and functionality in RA progression by using a longitudinal study in RA patients before and after methotrexate (MTX), anti-TNFα agents or rituximab treatments. A_2AARs were analyzed by saturation binding assays in lymphocytes from RA patients throughout the 24-month study timeframe. In an adjuvant-induced arthritis model in rats we showed the efficacy of the A_2AAR agonist, CGS 21680 in comparison with standard therapies by means of paw volume assessment, radiographic and ultrasonographic imaging. Arthritic-associated pain was investigated in mechanical allodynia and thermal hyperalgesia tests. IL-10 release following A_2AAR stimulation in lymphocytes from RA patients and in serum from arthritic rats was measured. In lymphocytes obtained from RA patients, the A_2AAR up-regulation was gradually reduced in function of the treatment time and the stimulation of these receptors mediated a significant increase of IL-10 production. In the same cells, CGS 21680 did not affected cell viability and did not produced cytotoxic effects. The A_2AAR agonist CGS 21680 was highly effective, as suggested by the marked reduction of clinical signs, in rat adjuvant-induced arthritis and associated pain. This study highlighted that A_2AAR agonists represent a physiological-like therapeutic alternative for RA treatment as suggested by the anti-inflammatory role of A_2AARs in lymphocytes from RA patients. The effectiveness of A_2AAR stimulation in a rat model of arthritis supported the role of A_2AAR agonists as potential pharmacological treatment for RA.

Investigation of Caucasian rheumatoid arthritis susceptibility loci in African patients with the same disease

INTRODUCTION

The largest genetic risk to develop rheumatoid arthritis (RA) arises from a group of alleles of the HLA DRB1 locus ('shared epitope', SE). Over 30 non-HLA single nucleotide polymorphisms (SNPs) predisposing to disease have been identified in Caucasians, but they have never been investigated in West/Central Africa. We previously reported a lower prevalence of the SE in RA patients in Cameroon compared to European patients and aimed in the present study to investigate the contribution of Caucasian non-HLA RA SNPs to disease susceptibility in Black Africans.

METHODS

RA cases and controls from Cameroon were genotyped for Caucasian RA susceptibility SNPs using Sequenom MassArray technology. Genotype data were also available for 5024 UK cases and 4281 UK controls and for 119 Yoruba individuals in Ibadan, Nigeria (YRI, HapMap). A Caucasian aggregate genetic-risk score (GRS) was calculated as the sum of the weighted risk-allele counts.

RESULTS

After genotyping quality control procedures were performed, data on 28 Caucasian non-HLA susceptibility SNPs were available in 43 Cameroonian RA cases and 44 controls. The minor allele frequencies (MAF) were tightly correlated between Cameroonian controls and YRI individuals (correlation coefficient 93.8%, p = 1.7E-13), and they were pooled together. There was no correlation between MAF of UK and African controls; 13 markers differed by more than 20%. The MAF for markers at PTPN22, IL2RA, FCGR2A and IL2/IL21 was below 2% in Africans. The GRS showed a strong association with RA in the UK. However, the GRS did not predict RA in Africans (OR = 0.71, 95% CI 0.29 - 1.74, p = 0.456). Random sampling from the UK cohort showed that this difference in association is unlikely to be explained by small sample size or chance, but is statistically significant with p<0.001.

CONCLUSIONS

The MAFs of non-HLA Caucasian RA susceptibility SNPs are different between Caucasians and Africans, and several polymorphisms are barely detectable in West/Central Africa. The genetic risk of developing RA conferred by a set of 28 Caucasian susceptibility SNPs is significantly different between the UK and Africa with p<0.001. Taken together, these observations strengthen the hypothesis that the genetic architecture of RA susceptibility is different in different ethnic backgrounds.

Associations between interleukin-10 polymorphisms and susceptibility to rheumatoid arthritis: a meta-analysis

The aim of this study was to determine whether the interleukin-10 (IL-10) polymorphisms confer susceptibility to rheumatoid arthritis (RA). A meta-analysis was conducted on the associations between the IL-10 -1082 G/A, -592 C/A, -892 C/T and IL-10.R polymorphisms and RA using; (1) allele contrast, (2) the recessive model, (3) the dominant model, and (4) the additive model. A total of 16 studies (19 comparisons) involving 2647 RA patients and 3383 controls were considered in the meta-analysis. Meta-analysis of the IL-10 -1082 G/A polymorphism showed no association with RA in the study subjects, or in European or Asian subjects. However, meta-analysis of the -1082 G allele in 4 studies in Hardy-Weinberg equilibrium showed a significant association with RA (OR=1.217, 95% CI=1.027-1.442, P=0.0236). In contrast, meta-analysis of the C allele, the CC genotype, and of the CC versus the AA genotype of the IL-10 -592 C/A polymorphism showed significant associations with RA. The overall ORs of the associations between the C allele and RA were 0.684 and 0.758 (95% CI=0.494-0.946, P=0.022; 95% CI=0.475-1.210, P=0.045) in all study subjects and Asians. Meta-analysis of the CC+CT versus TT genotype and of the CC versus TT genotype of the IL-10 -892 C/T polymorphism revealed significant associations with RA. The overall OR of the association between the C allele carrier and RA was 0.552 (95% CI=0.375-0.812, P=0.003). No association was found between the IL10.R2 alleles and RA. This meta-analysis suggests that the IL-10 -592 C/A polymorphism confers susceptibility to RA in Asians and that the IL-10 -1082 G/A and -892 C/T polymorphisms are associated with RA susceptibility. These findings suggest the IL-10 genes confer susceptibility to RA.

Interleukin-10 gene promoter polymorphism in Polish rheumatoid arthritis patients

Interleukin (IL)-10 is an important multifunctional cytokine with both anti-inflammatory and immunoregulatory effects in rheumatoid arthritis (RA). In the present study, we evaluated the frequency and potential impact of IL-10 promoter polymorphisms on susceptibility to and severity of RA in Polish in - patients with a high disease activity (mean DAS 28 C-reactive protein 5.25). DNA was obtained from 244 RA patients and 106 healthy controls. The -592C/A and -1082G/A IL-10 gene polymorphisms were amplified by polymerase chain reaction with restriction endonuclease mapping. The frequency of the IL-10-592CA, -592AA genotypes (respectively: 30% vs 5% and 7% vs 0%) and allele -592A (37% vs 5%) were significantly higher in RA patients as compared with a control group. We did not find any association of the IL-10-592C/A genotype distribution with disease parameters, except for an increased ESR (erythrocyte sedimentation rate) in patients with the -592CC genotype as compared with those with -592CA or -592AA genotypes (P = 0.01). The frequency of the IL-10-1082GG genotype was lower (P = 0.0001), and that of the IL-10-1082GA genotype was higher (P = 0.009) in RA patients comparing with the control group. In RA patients with -1082GA or -1082AA genotypes the time duration of the disease (P = 0.03), Health Assessment Questionnaire (HAQ) Score (P = 0.04) and PLT count (P = 0.001) were significantly increased as compared with subjects with -1082GG genotype. Presented findings indicate that IL-10-592C/A and IL-10-1082G/A polymorphisms may be considered genetic risk factors for RA susceptibility and severity.

Interleukin-1 receptor antagonist gene polymorphisms are associated with disease severity in Black South Africans with rheumatoid arthritis

OBJECTIVE

To test for genetic associations between polymorphisms of the interleukin-1 (IL-1) gene cluster and disease susceptibility and severity in Black South Africans with rheumatoid arthritis (RA).

METHODS

Allele and genotype frequencies of IL1B (-511) and (+3954) and IL1RN variable number of tandem repeat (VNTR) and (+2018) were compared between 141 RA patients and 101 healthy controls.

RESULTS

No significant differences in allelic distribution at the four loci were observed between RA patients and controls. Within the RA group, the IL1RN*2 (two repeats of an 86bp tandem repeat) at the IL1RN VNTR locus was independently associated with higher Larsen radiologic damage scores (LDS), corrected for disease duration (p=0.04). Moreover, the inferred haplotype, consisting of IL1RN*2 and (+2018) 'C' allele, was associated with significantly higher LDS, on average 15 points higher, compared to the base haplotype of IL1RN*long (three or more repeats) and (+2018) 'T' allele (p=0.009). The common IL1B (-511) 'T' allele was associated with a poorer modified health assessment questionnaire disability index (p=0.02).

CONCLUSION

Our findings provide further evidence of a possible role of polymorphisms of the IL-1 gene cluster in disease severity in RA, and particularly IL1RN*2 as a marker of erosive joint damage in Black South Africans with RA.

Serum insulin-like growth factor-axis and matrix metalloproteinases in patients with rheumatic arthritis or rheumatic heart disease

BACKGROUND

Insulin-like growth factor (IGF)-I plays an important role for maintaining cardiac functions. We clarified the unknown role of IGF-axis in rheumatic heart disease (RHD).

METHOD

Interleukin (IL)-10, growth hormone (GH), IGF, IGF binding protein (IGFBP)-3 and matrix metalloproteinase (MMP) were measured by ELISA and zymography in 30 age range-matched normal subjects (control), 36 patients with acute phase of rheumatoid arthritis (RA) with positive rheumatoid factor (RF) and C-reactive protein (CRP), and in 43 patients with RHD with negative RF and CRP.

RESULT

Compared with normal subjects, increased IL-10 level and decreased GH were found in RA group whereas unchanged IL-10 and decreased GH were found in RHD group. Compared with age range-matched normal subjects, decreased IGFBP-3, MMP-9 levels, unchanged IGF-I were found in RA group whereas decreased IGF-I levels, unchanged IGFBP3 and increased MMP-9 at age>30 years were found in RHD group. IGF-II was not changed in RA and RHD groups.

CONCLUSION

These findings may imply that during inflammatory phase, the levels of anti-inflammation was high and total IGF-I and IGF bioavailability were maintained in patients with RA. Our findings in RHD may speculate that the long-term reduction of GH and IGF-I as well as the compensating effects of upregulated MMP-9 activity may be partially involved in the long-term pathogenesis from RHD to heart failure. Decreased GH, decreased IGF-I and increased MMP-9 activities may be possible diagnostic markers in RHD for developing heart failure.

Immune response genes in the post-Q-fever fatigue syndrome, Q fever endocarditis and uncomplicated acute primary Q fever

BACKGROUND

The influence of immune response gene variations on the development of chronic complications of Q fever is presently unclear.

AIM

To compare the frequencies of allelic polymorphisms in immune response genes in different Q fever patient groups.

DESIGN

Genetic association study.

METHODS

We measured the frequencies of immune response gene variants in: (i) an expanded group of 31 post-Q-fever fatigue patients (QFS); (ii) 22 Q fever endocarditis patients (QFE); and (iii) 22 patients who made an uncomplicated recovery from their initial attack of primary acute Q fever, comparing them with various standard control panels from the general population.

RESULTS

There were significant differences between the three Q fever groups. QFS patients differed from both QFE and uncomplicated patients and controls in the frequency of carriage of HLA-DRB1*11 and of the 2/2 genotype of the interferon-gamma intron1 microsatellite. Carriage of the HLA DRB1*11 allele was associated with reduced interferon-gamma and IL-2 responses from PBMC stimulated with ligand in short-term culture. QFE showed differences in the IL-10 promoter microsatellites R and G and had higher frequencies of the TNF-alpha receptor II 196R polymorphism. Q fever patients who had made an uncomplicated recovery differed from those with QFS or QFE, but were not significantly different in allelic frequencies to the control panels.

DISCUSSION

These immunogenetic differences support the concept of different immune states in chronic Q fever, determined by genetic variations in host immune responses, rather than by solely properties of Coxiella burnetii.

Interleukin-10 promoter polymorphism in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease in which interleukin (IL)-10 plays an important role. There are, however, controversial reports that IL-10 promoter polymorphism may be an independent marker of susceptibility and severity of RA. The aim of the present study was to examine the IL-10 promoter polymorphism in patients with RA. We examined 95 patients with rheumatoid arthritis diagnosed according to the criteria of the American College of Rheumatology. Polymerase chain reaction amplification was used for analysis of the promoter polymorphism of the IL-10 gene. In RA patients, the prevalence of genotypes encoding high expression of IL-10 was observed. Nevertheless, there was no association between IL-10 genotypes and age at disease diagnosis, disease activity in a physician's global assessment, and joint and extra-articular involvement. There was also no correlation between IL-10 polymorphism and disease activity parameters--erythrocyte sedimentation rate, C-reactive protein, number of swollen and tender joints, and duration of morning stiffness. We suggest that IL-10 promoter polymorphism is not a genetic risk factor for RA activity.

Cytokine genotypes correlate with pain and radiologically defined joint damage in patients with juvenile rheumatoid arthritis

OBJECTIVES

Single nucleotide polymorphisms (SNPs) in cytokine genes have been associated with risk of a number of autoimmune diseases. Moreover, some SNPs are associated with variations in rates of in vitro gene expression, and it is therefore possible that these functional polymorphisms may differentially affect inflammatory processes and disease outcome. This project's objective was to determine whether cytokine genotypes correlate with disease outcomes in patients with juvenile rheumatoid arthritis (JRA).

METHODS

Genotypes of SNPs of pro-inflammatory cytokines, tumour necrosis factor-alpha -308G -->A, interleukin-6 (IL-6) -174G -->C and interferon-gamma +874G -->A, and anti-inflammatory, immunosuppressive cytokines, interleukin-10 -1082G -->A, -819C -->T and -592A -->C and transforming growth factor-beta1 (TGF-beta1) codon 10T -->C and codon 25G -->C, were determined for patients with JRA who previously participated in a long-term outcome study. Cytokine genotypes and clinical variables showing significant correlations with clinical outcomes at the alpha = 0.100 level in univariate analyses were entered in multivariate tests.

RESULTS

In multivariate tests, the IL-6 genotype -174G/G was positively correlated with pain [regression coefficient B = 0.899, 95% confidence intervals (CI) 0.185, 1.612, P = 0.014]. The homozygous TGF-beta1 codon 25G/G genotype showed a protective effect against joint space narrowing on radiographs taken within 2 yr of disease onset, but confidence intervals were wide [odds ratio (OR) 0.176, 95% CI 0.037, 0.837 P = 0.029].

CONCLUSIONS

The correlation of IL-6 genotype with pain and the possible association of the TGF-beta1 codon 25 genotype with short-term radiographic damage (G/C with greater risk and G/G with decreased risk) suggests that both these polymorphisms may be useful early prognostic indicators. Further studies of the relation between cytokine genotypes and outcomes in patients with all forms of juvenile idiopathic arthritis (JIA) are warranted.

Interleukin 10 promoter microsatellite polymorphisms are associated with response to long term treatment with etanercept in patients with rheumatoid arthritis

OBJECTIVES

To analyse the association of interleukin 10 (IL10) promoter polymorphisms, which have been shown to be related to IL10 secretion capacity, with the response to long term treatment with etanercept in patients with rheumatoid arthritis (RA).

METHODS

Fifty patients with active RA were treated for up to 4 years (median 39 months, range 3-52) with stable doses of etanercept as monotherapy. Treatment response was assessed as defined by the EULAR criteria in an intention to treat analysis, with the last observation carried forward. IL10 promoter microsatellite polymorphisms IL10.R and IL10.G were genotyped by fragment length analysis in patients and 189 healthy controls matched for ethnicity, age, and sex. Haplotypes were reconstructed using a method based on bayesian, coalescent theory with the PHASE software.

RESULTS

IL10 microsatellite polymorphisms were not associated with susceptibility to RA. When patients with good treatment response (n = 25) were compared with patients with moderate (n = 17) or no response (n = 8), a significantly different distribution of the prevailing alleles R2, R3 and G9, G13, respectively, became evident. Good treatment response was associated with carriage of the R3 allele or R3-G9 haplotype, whereas the allele G13 and the haplotype R2-G13 predominated in patients with moderate or no response.

CONCLUSION

Genotyping of the IL10 promoter microsatellites may be useful in predicting the clinical response to etanercept in patients with RA. The high prevalence of the presumptive IL10 low producer allele R3 in patients with a favourable response suggests that IL10 promotes disease activity in RA under the specific condition of tumour necrosis factor antagonism.

No relationship of -627 interleukin-10 promoter polymorphism in Chinese patients with rheumatoid arthritis

The aim of this study was to examine whether -627 interleukin-10 (IL-10) promoter polymorphism is a marker of susceptibility to or severity of rheumatoid arthritis (RA) in Chinese patients in Taiwan. The study included 198 Chinese patients with RA. One hundred unrelated healthy individuals living in central Taiwan served as the control subjects. The relationship between IL-10 gene polymorphism and clinical manifestations of RA was evaluated. For the genotype, allelic frequency, and carriage rate of IL-10 polymorphism, there were no statistically significant differences found between patients and controls. Furthermore, we did not detect any association of IL-10 genotype with rheumatoid factor (RF), extra-articular involvement, or bone erosion in the RA patients. The lack of association of -627 IL-10 gene polymorphism with RA and the clinical findings in our study implies that the IL-10 gene polymorphism cannot serve as a candidate gene marker for screening RA patients.

Genetics in rheumatoid arthritis

This chapter reviews the latest original research on the genetics of rheumatoid arthritis (RA), with a focus on its relevance for the clinical rheumatologist. The following questions will be dealt with in order to appreciate the recent progress in this field. * Why is a knowledge of genetics useful for an understanding of the pathogenesis of RA? * Is a knowledge of genetic risk factors relevant for day-to-day clinical practice? * What methods are used for identifying genetic risk factors? * Which genetic regions have been identified in susceptibility to RA? * What risk factors have been identified? * What are the future prospects and research agenda?

Ethnic differences in allelic distribution of IFN-g in South African women but no link with cervical cancer

BACKGROUND: The failure of specific types of human papillomaviruses (HPV) to raise effective immune responses may be important in the pathogenesis of cervical cancer, the second most common cancer in South African women. Polymorphisms of a number of cytokine genes have been implicated in inducing susceptibility or resistance to cancers caused by infectious agents owing to their role in determining host immune response. Polymorphisms of IL-10 and IFN-gamma genes are believed to influence the expression and/or secretion levels of their respective cytokines. METHODS AND RESULTS: In this study, women with histologically proven cancer of the cervix (n = 458) and hospital-based controls (n = 587) were investigated for bi-allelic -1082 (A/G) polymorphisms of IL-10 and the bi-allelic +874(A/T) polymorphisms of IFN-gamma. In addition, the distributions of the allelic frequencies were stratified in both the African and mixed race population groups of South Africa. We found striking differences in the allele distribution of IFN-gamma (X2 = 0.02) among the two ethnic groups. A significant increase in the allele distribution of the IFN-gamma AA genotype was found in the African group compared to the mixed population group (OR, 0.5; 95% CI, 0.2-1.0). For IL-10 there were no significant allelic differences between the two South African ethnic groups. Furthermore, when the ethnic groups were combined the IL-10 allelic frequencies in the combined South African data were similar to those observed in an Oriental population from Southern China and in an Italian population. However, the allele frequencies of the IFN-gamma genotype among the two South African ethnic groups were different when compared to an Italian Caucasoid group. While crude analysis of these data showed both statistically significantly increased and diminished risks of cervical cancer among high producers of INF-gamma and low producers of IL-10 respectively, these associations were no longer significant when the data were adjusted for confounding factors. CONCLUSION: These findings demonstrate a clear correlation between ethnicity and IFN-gamma polymorphism across different population groups. However, these differences in ethnicity and gene polymorphisms in the aforementioned cytokines are suggested not to influence the development of invasive cervical cancer but may represent an important susceptibility biomarker for other diseases and should be explored further.