Association of ferritin autoantibodies with giant cell arteritis/polymyalgia rheumatica.

OBJECTIVES: Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) are relatively common inflammatory disorders. Establishing the diagnosis however may be difficult, since so far no specific biomarkers of the disorders are available. METHODS: As a screening procedure, the authors used protein arrays for the detection of new autoantigens in GCA and PMR. The results of the protein array were confirmed by different ELISAs detecting IgG antibodies against the human ferritin heavy chain, N-terminal 27 amino acids of the human ferritin heavy chain or the homologous peptide of Staphylococcus epidermidis. Sera of patients with only GCA (n=64), only PMR (n=47) and both PMR and GCA (n=31) were used. RESULTS: In the ELISA using the human ferritin peptide, the sensitivity of IgG antibodies against ferritin was 92% in 36 GCA and/or PMR patients before initiation of treatment, 22/32 (69%) in patients with disease flares and 64/117 (55%) in the total cohort including treated and inactive patients. In controls, the false positive rate was 11/38 (29%) in systemic lupus erythematosus, 1/36 (3%) in rheumatoid arthritis, 0/31 (0%) in late onset rheumatoid arthritis, 3/46 (6.5%) in B-non-Hodgkin's lymphoma and 1/100 (1%) in blood donors. In the ELISA using the ferritin peptide of S epidermidis, 89% of 27 patients with untreated GCA and PMR were positive. CONCLUSION: Antibodies against the ferritin peptide were present in up to 92% of untreated, active GCA and PMR patients. They can be useful as a diagnostic marker of PMR and GCA.

Evidence of the contribution of the X chromosome to systemic sclerosis susceptibility: association with the functional IRAK1 196Phe/532Ser haplotype.

OBJECTIVE: Several autoimmune disorders, including systemic sclerosis (SSc), are characterized by a strong sex bias. To date, it is not known whether genes on the sex chromosomes influence SSc susceptibility. Recently, an IRAK1 haplotype that contains the 196Phe functional variant (rs1059702), located on Xq28, was found to confer susceptibility to systemic lupus erythematosus (SLE). This study was undertaken to test for an association between SSc and the IRAK1 SLE risk haplotype. METHODS: We tested for an association with the IRAK1 SLE risk haplotype in a discovery set of 849 SSc patients and 625 controls. IRAK1 rs1059702 was further genotyped in a replication set, which included Caucasian women from Italy (493 SSc patients and 509 controls) and Germany (466 SSc patients and 1,083 controls). RESULTS: An association between the IRAK1 haplotype and SSc was detected in the discovery set. In both the discovery and replication sets, the rs1059702 TT genotype was found to be associated with specific SSc subsets, highlighting a potential contribution to disease severity. A meta-analysis provided evidence of an association of both the T allele and TT genotype with the overall disease, with an odds ratio (OR) of 1.20 and 95% confidence interval (95% CI) of 1.06-1.35 for the T allele (P = 0.003) and an OR of 1.49 and 95% CI of 1.06-2.10 for the TT genotype (P = 0.023). However, the most notable associations were observed with the diffuse cutaneous, anti-topoisomerase I antibody positive, and SSc-related fibrosing alveolitis subsets (OR 2.35 [95% CI 1.51-3.66], P = 1.56 × 10(-4), OR 2.84 [95% CI 1.87-4.32], P = 1.07 × 10(-6), and OR 2.09 [95% CI 1.35-3.24], P = 9.05 × 10(-4), respectively). CONCLUSION: Our study provides the first evidence of an association between IRAK1 and SSc, demonstrating that a sex chromosome gene directly influences SSc susceptibility and its phenotypic heterogeneity.

[Genetic analysis in collagen vascular diseases]. / Genetik bei Kollagenosen.

Genetic risk factors are known to exist for all collagen vascular diseases. They are most important for systemic lupus erythematosus (SLE) and systemic scleroderma (SSc), as shown by the systematic analysis of family data. Both diseases to date share most of the validated risk factors (PTPN22, STAT4, BANK1, TNFAIP3, IRF5, BLK) underlining once again their relationship. Moreover, most of these factors were also shown to be associated with other autoimmune diseases. Many additional risk factors exist, but need further analysis. The HLA complex is of special interest, as many loci within this region, some highly polymorphic, may contribute to the total genetic risk.

Association of the CD226 Ser(307) variant with systemic sclerosis: evidence of a contribution of costimulation pathways in systemic sclerosis pathogenesis.

OBJECTIVE: The nonsynonymous polymorphism rs763361 of the CD226 gene, which encodes DNAX accessory molecule 1, which is involved in T cell costimulation pathways, has recently been identified as a genetic risk factor for autoimmunity. The purpose of this study was to test for association of the CD226 rs763361 polymorphism with systemic sclerosis (SSc) in European Caucasian populations. METHODS: CD226 rs763361 was genotyped in 3,632 individuals, consisting of a discovery sample (991 SSc patients and 1,008 controls) and a replication sample (999 SSc patients and 634 controls). All study subjects were of European Caucasian origin. Expression of CD226 was assessed on peripheral blood mononuclear cells obtained from 21 healthy donors genotyped for CD226 rs763361. RESULTS: The CD226 rs763361 T allele was found to be associated with SSc in both the discovery and the replication samples, showing the following results in the combined populations: odds ratio (OR) 1.22 (95% confidence interval [95% CI] 1.10-1.34), P = 5.69 × 10(-5) . The CD226 T allele was also associated with various SSc subsets, highlighting a potential contribution to disease severity. The most remarkable associations of the CD226 TT risk genotype were observed with the diffuse cutaneous SSc subtype, the anti-topoisomerase I antibody-positive, and SSc-related fibrosing alveolitis subsets: OR 1.86 (95% CI 1.42-2.43), P = 5.15 × 10(-6) , OR 1.82 (95% CI 1.38-2.40), P = 2.16 × 10(-5) , and OR 1.61 (95% CI 1.25-2.08), P = 2.73 × 10(-4) , respectively. CD226 expression was not significantly influenced by CD226 rs763361 genotypes whatever the T cell subtype investigated. CONCLUSION: Our results establish CD226 as a new SSc genetic susceptibility factor underlying the contribution of costimulation pathways in the pathogenesis of SSc. Further work is nevertheless needed to define the causal variant at the CD226 locus as well as the functional consequences.

NLRP1 influences the systemic sclerosis phenotype: a new clue for the contribution of innate immunity in systemic sclerosis-related fibrosing alveolitis pathogenesis.

BACKGROUND: Recent evidence has highlighted a potential role of interleukin 1ß (IL-1ß) in systemic sclerosis (SSc). NLRP1 provides a scaffold for the assembly of the inflammasome that promotes the processing and maturation of pro-IL-1ß. In addition, NLRP1 variants were found to confer susceptibility to autoimmune disorders. OBJECTIVE: /st> To study a possible association of the NLRP1 rs6502867, rs2670660 and rs8182352, rs12150220 and rs4790797 with SSc in the European Caucasian population. METHODS: NLRP1 single nucleotide polymorphisms were genotyped in 3227 individuals comprising a discovery set (870 SSc patients and 962 controls) and a replication set including individuals from Germany (532 SSc patients and 324 controls) and Italy (527 SSc patients and 301 controls), all individuals being of European Caucasian origin. RESULTS: Conditional analyses revealed a significant association for the NLRP1 rs8182352 variant with both anti-topoisomerase-positive and SSc-related fibrosing alveolitis (FA) subsets under an additive model: p=0.0042, OR 1.23 (95% CI 1.07 to 1.41) and p=0.0065 OR 1.19 (95% CI 1.05 to 1.36), respectively. Logistic regression analysis showed an additive effect of IRF5 rs2004640, STAT4 rs7574865 and NLRP1 rs8182352 risk alleles on SSc-related FA. CONCLUSIONS: Our results establish NLRP1 as a new genetic susceptibility factor for SSc-related pulmonary fibrosis and anti-topoisomerase-positive SSc phenotypes. This provides new insights into the pathogenesis of SSc, underlining the potential role of innate immunity in particular in the FA-positive SSc subphenotype, which represents a severe subset of the disease.

Association of the TNFAIP3 rs5029939 variant with systemic sclerosis in the European Caucasian population.

BACKGROUND: TNFAIP3 encodes the ubiquitin-modifying enzyme, a key regulator of inflammatory signalling pathways. Convincing associations between TNFAIP3 variants and autoimmune diseases have been reported. OBJECTIVE: To investigate the association of TNFAIP3 polymorphisms with systemic sclerosis (SSc). METHODS: Three single nucleotide polymorphisms (SNPs) in a set of 1018 patients with SSc and 1012 controls of French Caucasian origin were genotyped. Two intergenic SNPs, rs10499194 and rs6920220, and one located in TNFAIP3 intron 2, rs5029939, were selected. The TNFAIP3 rs5029939 found to be associated with SSc in this first set was then genotyped in a second set of 465 patients with SSc and 182 controls from Germany and 184 patients with SSc and 124 controls from Italy. Pooled odd ratios were calculated by Mantel-Haenszel meta-analysis. RESULTS: The rs5029939 G allele was found to be significantly associated with SSc susceptibility (pooled OR=2.08 (95% CI 1.59 to 2.72); p=1.16×10⁻7), whereas the rs10499194 and rs6920220 variants displayed no association. Only one of the predicted haplotypes investigated in the French sample was significantly associated with SSc (p=8.91×10⁻8), and this haplotype was discriminating only in the presence of the rs5029939 risk allele, suggesting that this SNP tags the association signal. The strongest associations of rs5029939 with subphenotypes, having large magnitudes for complex genetic disorders, were observed for diffuse cutaneous SSc (pooled OR=2.71 (1.94 to 3.79), p=5.2×10⁻9), fibrosing alveolitis (pooled OR=2.26 (1.61 to 3.17), p=2.5×10⁻6) and pulmonary arterial hypertension (pooled OR=3.11 (1.86 to 5.17), p=1.3×10⁻5). CONCLUSION: These results suggest that TNFAIP3 is a genetic susceptibility factor for SSc.

Association of a KCNA5 gene polymorphism with systemic sclerosis-associated pulmonary arterial hypertension in the European Caucasian population.

OBJECTIVE: Pulmonary arterial hypertension (PAH) has emerged as a leading cause of death in systemic sclerosis (SSc). The genetic basis of PAH has been unraveled in recent years, with a major role played by transforming growth factor ß receptors; however, some other candidate genes have also been advocated, including potassium voltage-gated channel, shaker-related subfamily, member 5 (KCNA5). We undertook this study to determine whether KCNA5 polymorphisms confer susceptibility to SSc and its vascular phenotype, including PAH. METHODS: Four KCNA5 single-nucleotide polymorphisms (SNPs), rs10744676, rs1860420, rs3741930, and rs2284136, were genotyped in a discovery set of 638 SSc patients and 469 controls. In addition, rs10744676 was genotyped in an independent replication sample (938 SSc patients and 564 controls) and in a cohort of 168 patients with different PAH subtypes. RESULTS: The KCNA5 rs10744676 variant was found to be associated with SSc in the discovery sample, with an odds ratio (OR) of 0.62 (95% confidence interval [95% CI] 0.48-0.79, adjusted P = 0.0003) in comparison with controls (C allele frequency 11.4% versus 17.2%). When subphenotypes were investigated, an association was found solely for PAH associated with SSc (OR 0.31 [95% CI 0.13-0.71], adjusted P = 0.04). The other KCNA5 SNPs tested were not associated with any SSc subset. The above association with PAH associated with SSc was replicated in the second set. In the combined population, rs10744676 was strongly associated with PAH associated with SSc in comparison with controls (OR 0.36 [95% CI 0.21-0.63], P = 0.0002). In the independent cohort of patients with PAH, after investigating PAH subtypes, only rs10744676 showed an association with PAH associated with SSc. CONCLUSION: Our results provide the first evidence for an association between the KCNA5 rs10744676 variant and PAH associated with SSc.

BANK1 is a genetic risk factor for diffuse cutaneous systemic sclerosis and has additive effects with IRF5 and STAT4.

OBJECTIVE: To determine whether the functional BANK1 variants rs3733197 and rs10516487 are associated with systemic sclerosis (SSc) in 2 European Caucasian populations and to investigate the putative gene-gene interactions between BANK1 and IRF5 as well as STAT4. METHODS: BANK1 single-nucleotide polymorphisms were genotyped in a total population of 2,432 individuals. The French cohort consisted of 874 SSc patients and 955 controls (previously genotyped for both IRF5 rs2004640 and STAT4 rs7574865). The German cohort consisted of 421 SSc patients and 182 controls. RESULTS: The BANK1 variants were found to be associated with diffuse cutaneous SSc (dcSSc) in both cohorts, providing an odds ratio (OR) of 0.77 for the rs10516487 T rare allele in the combined populations of dcSSc patients as compared with the combined populations of controls (95% confidence interval [95% CI] 0.64-0.93) and an OR of 0.73 (95% CI 0.61-0.87) for the rs3733197 A rare allele. BANK1 haplotype analysis found the A-T haplotype to be protective in dcSSc patients (OR 0.70 [95% CI 0.57-0.86], P = 3.39 x 10(-4)) and the G-C haplotype to be a risk factor (OR 1.25 [95% CI 1.06-1.47], P = 0.008). Significant differences were also observed when the limited cutaneous subset of SSc was compared with the dcSSc subset, both for the rare alleles and for the haplotypes. The BANK1, IRF5, and STAT4 risk alleles displayed a multiplicatively increased risk of dcSSc of 1.43-fold. CONCLUSION: Our results establish BANK1 as a new SSc genetic susceptibility factor and show that BANK1, IRF5, and STAT4 act with additive effects.

Association of rheumatoid arthritis with Mdm2 SNP309 and genetic evidence for an allele-specific interaction between MDM2 and p53 P72R variants: a case control study.

OBJECTIVE: This study examines two common, functional, single nucleotide polymorphisms (SNP) in the genes coding the human homolog of murine-double-minute-2 (MDM2) and p53 in patients with rheumatoid arthritis (RA) based on the hypothesis that p53 may be an important negative regulator of the pro-inflammatory transcription factor nuclear factor kappa b (NFKappaB). METHODS: Genomic DNA was obtained from 221 patients with RA who fulfilled at least 4 ACR criteria and from 521 healthy controls. Mdm2 SNP309 and p53 P72R were genotyped by polymerase chain reaction and restriction enzyme analysis. RESULTS: In RA patients the frequencies of the mdm2 SNP309 G allele and both G-containing genotypes were significantly reduced (G allele: OR: 0.75, 95% CI: 0.59-0.95, p=0.016; genotype TG: OR: 0.71, 95% CI: 0.50-1.00; genotype GG: OR. 0.58, 95% CI: 0.34-0.99; both: p=0.049). Concerning p53 P72R, no differences in allele or genotype frequencies were detected. A combined analysis of both polymorphisms revealed a significant interaction between them (p=0.046). In individuals carrying >1 p53 72R allele, MDM2 had a protective effect, whereas in individuals homozygous for p53 72P, MDM2 had the opposite effect. CONCLUSION: The function of MDM2 depends on the p53 P72R genotype, resulting in either an increased or reduced risk for RA. We suggest that in most cases MDM2 stabilizes the conformation of p53, whereas in p53 PP-positive subjects MDM2 supports the degradation of p53.

Comparison of patients with and without digital ulcers in systemic sclerosis: detection of possible risk factors.

BACKGROUND: Digital ulcers (DU) are a major complication in the course of systemic sclerosis (SSc). In recent years, efficacious, but expensive therapies (e.g. iloprost, sildenafil, bosentan) have been shown to improve healing or to reduce the recurrence of DU. For optimal management it would be useful to identify the risk factors for DU. Such statistical analyses have been rare because they require a high number of patients. OBJECTIVES: To identify potential risk factors for DU in patients with SSc. METHODS: We used the registry of the German Network for Systemic Scleroderma and evaluated the data of 1881 patients included by August 2007. We assessed potential risk factors for DU by comparing patients with (24.1%) and without active DU at time of entry (75.9%). RESULTS: Multivariate analysis revealed that male sex, presence of pulmonary arterial hypertension (PAH), involvement of the oesophagus, diffuse skin sclerosis (only when PAH was present), anti-Scl70 antibodies, young age at onset of Raynaud's phenomenon (RP), and elevated erythrocyte sedimentation rate (ESR) significantly impacted on the appearance of DU. Certain combinations increased the patients' probability of presenting with DU, with the highest probability (88%) for male patients with early onset of RP, ESR>30 mm h(-1), anti-Scl70 antibodies and PAH. Patients with DU developed RP, skin sclerosis and organ involvement approximately 2-3 years earlier than patients without DU. CONCLUSIONS: The results reveal possible risk factors for the occurrence of DU in SSc. As DU are prone to local complications, prophylactic vasoactive treatment for patients presenting with these factors may be justified.

Skin sclerosis is only of limited value to identify SSc patients with severe manifestations--an analysis of a distinct patient subgroup of the German Systemic Sclerosis Network (DNSS) Register.

OBJECTIVES: In SSc, diagnosis and classification is based mainly on skin sclerosis. Herein, we investigated in a large multicentre cohort, to what extent skin sclerosis reflects organ involvement and additional clinical symptoms. METHODS: A total of 1200 SSc patients from the register of the German Systemic Sclerosis Network (DNSS), classified as either lcSSc or dcSSc, were analysed for their serological characteristics, clinical symptoms and organ manifestations in relation to skin involvement measured by the modified Rodnan skin score (mRSS). RESULTS: SSc patients with different mRSS did not differ significantly in their disease duration and in most of the clinical symptoms. They showed a similar distribution of most organ manifestations such as pulmonary arterial hypertension as well as cardiac, renal and nervous system involvement. More severe skin thickening was found to be associated with pulmonary fibrosis and gastrointestinal symptoms, as well as with digital ulcers and musculoskeletal involvement. CONCLUSIONS: In patients with SSc, potentially life-threatening complications and clinical symptoms with high impact on the quality of life occur independently from the extent of skin sclerosis. The diagnosis in SSc patients with a low mRSS could be missed or they could be insufficiently treated.

[Relevance of the gene variant PTPN22 620W for rheumatology]. / Zur Bedeutung der Genvariante PTPN22 620W für die Rheumatologie.

PTPN22 620W is regarded as the second most important risk factor for type 1 diabetes and rheumatoid arthritis. Here we describe aspects of the molecular biology of the enzyme and its function, the geographical distribution of the 620W variant, as well as its importance in less frequent rheumatic diseases.

The registry of the German Network for Systemic Scleroderma: frequency of disease subsets and patterns of organ involvement.

OBJECTIVE: Systemic sclerosis (SSc) is a rare, heterogeneous disease, which affects different organs and therefore requires interdisciplinary diagnostic and therapeutic management. To improve the detection and follow-up of patients presenting with different disease manifestations, an interdisciplinary registry was founded with contributions from different subspecialties involved in the care of patients with SSc. METHODS: A questionnaire was developed to collect a core set of clinical data to determine the current disease status. Patients were grouped into five descriptive disease subsets, i.e. lcSSc, dcSSc, SSc sine scleroderma, overlap-syndrome and UCTD with scleroderma features. RESULTS: Of the 1483 patients, 45.5% of patients had lcSSc and 32.7% dcSSc. Overlap syndrome was diagnosed in 10.9% of patients, while 8.8% had an undifferentiated form. SSc sine scleroderma was present in 1.5% of patients. Organ involvement was markedly different between subsets; pulmonary fibrosis for instance was significantly more frequent in dcSSc (56.1%) than in overlap syndrome (30.6%) or lcSSc (20.8%). Pulmonary hypertension was more common in dcSSc (18.5%) compared with lcSSc (14.9%), overlap syndrome (8.2%) and undifferentiated disease (4.1%). Musculoskeletal involvement was typical for overlap syndromes (67.6%). A family history of rheumatic disease was reported in 17.2% of patients and was associated with early disease onset (P < 0.005). CONCLUSION: In this nationwide register, a descriptive classification of patients with disease manifestations characteristic of SSc in five groups allows to include a broader spectrum of patients with features of SSc.

[Organ-specific diagnosis in patients with systemic sclerosis: Recommendations of the German Network for Systemic Sclerosis (DNSS)]. / Organspezifische Diagnostik von Patienten mit systemischer Sklerodermie : Empfehlungen des Deutschen Netzwerkes für Systemische Sklerodermie (DNSS).

The diagnosis and therapy of systemic sclerosis (SSc) is demanding due to its nature as a multisystem disease and its chronic, severe course. To date, there are no generally accepted recommendations for diagnostic work-up either for the time of initial disease diagnosis or for the regular follow-up clinical examinations and diagnostic procedures required. However, due to recent advances, e.g. in the therapy of pulmonary arterial hypertension, regular examinations may contribute to early recognition and treatment of developing organ involvement. This manuscript describes the recommendations for initial and follow-up organ-specific clinical examinations and diagnostic work-up as compiled and carried out by the German Network for Systemic Scleroderma [Deutsche Netzwerk für systemische Sklerodermie (DNSS)].

[A gene defect in the promoter of the endothelial NO synthase as a risk factor for rheumatoid arthritis]. / Gendefekt im Promoter der endothelialen NO-Synthase als Risikofaktor für Rheumatoide Arthritis.

The risk to develop rheumatoid arthritis (RA) includes environmental as well as genetic factors. Moreover, RA, being an inflammatory disease, is itself considered to be a risk factor for coronary artery disease, as it - or its treatment - may lead to endothelial dysfunction. Likewise, a single nucleotide polymorphism in the promoter of the endothelial NO synthase ((-786)C/T) leads to endothelial dysfunction in (-786)CC homozygous individuals. This genetic defect occurs in significantly higher frequencies in patients with RA, and therefore must be regarded as a genetic risk factor for RA.

[Immunogenetics--HLA-association, molecular chaperones and "related" diseases]. / Immungenetik -- HLA-Assoziation, molekulare Gouvernanten und "verwandte" Krankheiten.

The association of rheumatoid arthritis (RA) with the HLA complex has been well established since 1978. But what does that mean? After reminding the reader of some existing immunological interpretations, a more recent variant is introduced. Antigens and molecular chaperones of the HSP70 family form complexes, which interact with HLA-DR beta-chains, especially of the DRB1*0401 genotype, which is the most common among patients with RA in our region. This mechanism might bring *0401(+) persons an advantage in defence against microorganisms, but a disadvantage concerning autoimmunity. Chaperone machines are upregulated in synovial tissue of RA patients. As their number and variety is huge in humans, there exist many possibilities for function, reaching from antigen presentation to immune regulation. In addition to the HLA complex, the "genetic background" plays an important role for the development of an autoimmune disease. This is demonstrated in families of patients with RA or scleroderma, where a high percentage of first degree relatives suffer from a "related" disease.

Specific stimulation of peripheral blood mononuclear cells from patients with acute myocarditis by peptide-bound flavin adenine dinucleotide (FAD), a naturally occurring autologous hapten.

The tryptic FAD-peptide carrying the flavin in 8alpha-(N3)histidyl linkage as natural hapten was isolated by HPLC from the bacterial enzyme 6-hydroxy-d-nicotine oxidase. The same flavin protein linkage is found in the mitochondrial succinate dehydrogenase flavoprotein subunit, the predominant flavoprotein with covalently bound FAD in mitochondria of cardiomyocytes. Peripheral blood mononuclear cells (PBMC) were isolated from four patients with acute myocarditis, seven patients with dilated cardiomyopathy (DCM) and from four healthy control individuals. The response of PBMC to the FAD-peptide was evaluated by measuring proliferation ([3H]-dThd incorporation) and cytokine secretion [interferon (IFN)-gamma]. PBMC from all patients with acute myocarditis showed positive responses to the FAD-peptide, in contrast to PBMC from patients with DCM or control individuals. Following the recovery of the patients from the acute inflammation of the heart, PBMC no longer exhibited a proliferation response to the FAD-peptide. A chemically synthesized FAD-free peptide with identical amino acid sequence induced no response of PBMC. The results are consistent with a recall response by activated T cells, specific for the normally cryptic mitochondrial flavin-hapten, which may be liberated following cardiomyocyte destruction during the inflammation of the heart.