HLA sequencing identifies novel associations and suggests clinical relevance of DPB1*04:01 in ANCA-associated Granulomatosis with polyangiitis

Granulomatosis with polyangiitis (GPA) is a rare systemic autoimmune disease. Major contributions of HLA genes have been reported; however, HLA typing-based diagnosis or risk prediction in GPA has not been established. We have performed a sequencing-based HLA genotyping in a north Indian GPA cohort and controls to identify clinically relevant novel associations. PR3-ANCA-positive 40 GPA patients and 40 healthy controls from north India were recruited for the study. Targeted sequencing of HLA-A,-B,-C,-DRB1,-DQB1, and -DPB1 was performed. Allelic and haplotypic associations were tested. Molecular docking of susceptibility HLA alleles with reported super-antigen epitopes was performed. The association of substituted amino acids located at the antigen-binding domain of HLA was evaluated. Genetic association of five HLA-alleles was identified in GPA. The novel association was identified for C*15:02 (p = 0.04; OR = 0.27(0.09-0.88)). The strongest association was observed for DPB1*04:01 (p < 0.0001; OR = 6.2(3.08-11.71)), previously reported in European studies. 35 of 40 GPA subjects had at least one DPB1*04:01 allele, and its significant risk was previously not reported from the Indian population. Significantly associated haplotypes DRB1*03:01-DQB1*02:01-DPB1*04:01 (p = 0.02; OR = 3.46(1.11-12.75)) and DRB1*07:01-DQB1*02:02-DPB1*04:01 (p = 0.04; OR = 3.35(0.95-14.84)) were the most frequent in GPA patients. Ranging from 89 % to 100 % of GPA patients with organ involvement can be explained by at least one DPB1*04:01 allele. A strong interaction between the HLA and three epitopes of the reported super antigen TSST-1 of Staphylococcus aureus was confirmed. Our study highlighted the potential applicability of HLA typing for screening and diagnosis of GPA. A large multi-centric study and genotype-phenotype correlation analysis among GPA patients will enable the establishment of HLA-typing based GPA diagnosis.

Activation of a Latent Epitope Causing Differential Binding of Antineutrophil Cytoplasmic Antibodies to Proteinase 3

OBJECTIVE

Proteinase 3 (PR3) is the major antigen for antineutrophil cytoplasmic antibodies (ANCAs) in the systemic autoimmune vasculitis, granulomatosis with polyangiitis (GPA). PR3-targeting ANCAs (PR3-ANCAs) recognize different epitopes on PR3. This study was undertaken to study the effect of mutations on PR3 antigenicity.

METHODS

The recombinant PR3 variants, iPR3 (clinically used to detect PR3-ANCAs) and iHm5 (containing 3 point mutations in epitopes 1 and 5 generated for epitope mapping studies) immunoassays and serum samples from patients enrolled in ANCA-associated vasculitis (AAV) trials were used to screen for differential PR3-ANCA binding. A patient-derived monoclonal ANCA 518 (moANCA518) that selectively binds to iHm5 within the mutation-free epitope 3 and is distant from the point mutations of iHm5 was used as a gauge for remote epitope activation. Selective binding was determined using inhibition experiments.

RESULTS

Rather than reduced binding of PR3-ANCAs to iHm5, we found substantially increased binding of the majority of PR3-ANCAs to iHm5 compared to iPR3. This differential binding of PR3-ANCA to iHm5 is similar to the selective moANCA518 binding to iHm5. Binding of iPR3 to monoclonal antibody MCPR3-2 also induced recognition by moANCA518.

CONCLUSION

The preferential binding of PR3-ANCAs from patients, such as the selective binding of moANCA518 to iHm5, is conferred by increased antigenicity of epitope 3 on iHm5. This can also be induced on iPR3 when captured by monoclonal antibody MCPR2. This previously unrecognized characteristic of PR3-ANCA interactions with its target antigen has implications for studying antibody-mediated autoimmune diseases, understanding variable performance characteristics of immunoassays, and design of potential novel treatment approaches.

Profile of circulating extracellular vesicles microRNA correlates with the disease activity in granulomatosis with polyangiitis

Granulomatosis with polyangiitis is a chronic systemic inflammation of small vessels characterized by circulating anti-proteinase 3 antibodies. MicroRNAs are short transcripts specifically inhibiting protein translation. Neutrophils can release extracellular vesicles (EVs). In this study, we characterized profile of microRNA trafficked by EVs in GPA. Fifty patients with GPA were enrolled in the study, 25 at acute phase and 25 in remission. EVs were isolated from the blood serum, characterized by their number, size distribution. Following unbiased screening for microRNA expression, differentially expressed candidates were measured by quantitative real-time PCR. Circulating DNA-myeloperoxidase complexes and apoptosis-related transcripts in peripheral blood neutrophils were quantified. We identified four differentially expressed microRNAs from EVs in granulomatosis with polyangiitis (GPA). MirRs-223-3p, 664a-3p, and 200b-3p were overexpressed and miR-769-5p suppressed in the disease. A distinction between GPA and healthy controls was the best for miR-223-3p, whereas miR-664a-3p discriminated between active vs. remission of GPA. Correct classification of the disease based on multivariate discriminant analysis was between 92% for acute phase and 85% for all study participants. Bioinformatics tools identified genes transcripts potentially targeted by the microRNAs belonging to pathways of focal adhesion, mTOR signaling and neutrophil extracellular traps formation. Two microRNAs positively correlating with the disease activity were involved in neutrophil extracellular traps formation and apoptosis inhibition. A comprehensive characteristics of microRNAs trafficked in bloodstream inside EVs correlates well with our understanding of the mechanisms of GPA and suggests the importance of EVs in progression of the disease.

Comprehensive characterization of central BCL-2 family members in aberrant eosinophils and their impact on therapeutic strategies

Purpose

Hypereosinophilia represents a heterogenous group of severe medical conditions characterized by elevated numbers of eosinophil granulocytes in peripheral blood, bone marrow or tissue. Treatment options for hypereosinophilia remain limited despite recent approaches including IL-5-targeted monoclonal antibodies and tyrosine kinase inhibitors.

Methods

To understand aberrant survival patterns and options for pharmacologic intervention, we characterized BCL-2-regulated apoptosis signaling by testing for BCL-2 family expression levels as well as pharmacologic inhibition using primary patient samples from diverse subtypes of hypereosinophilia (hypereosinophilic syndrome n = 18, chronic eosinophilic leukemia not otherwise specified n = 9, lymphocyte-variant hypereosinophilia n = 2, myeloproliferative neoplasm with eosinophilia n = 2, eosinophilic granulomatosis with polyangiitis n = 11, reactive eosinophilia n = 3).

Results

Contrary to published literature, we found no difference in the levels of the lncRNA Morrbid and its target BIM. Yet, we identified a near complete loss of expression of pro-apoptotic PUMA as well as a reduction in anti-apoptotic BCL-2. Accordingly, BCL-2 inhibition using venetoclax failed to achieve cell death induction in eosinophil granulocytes and bone marrow mononuclear cells from patients with hypereosinophilia. In contrast, MCL1 inhibition using S63845 specifically decreased the viability of bone marrow progenitor cells in patients with hypereosinophilia. In patients diagnosed with Chronic Eosinophilic Leukemia (CEL-NOS) or Myeloid and Lymphatic Neoplasia with hypereosinophilia (MLN-Eo) repression of survival was specifically powerful.

Conclusion

Our study shows that MCL1 inhibition might be a promising therapeutic option for hypereosinophilia patients specifically for CEL-NOS and MLN-Eo.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-021-03827-9.

Familial Eosinophilic Granulomatosis with Polyangiitis in a Sister and Brother

Eosinophilic granulomatosis with polyangiitis (EGPA) is a vasculitis characterized by an abnormally high number of eosinophils in the peripheral blood and tissues. EGPA is an extremely rare disorder, with an incidence of 0.5 to 3.7 new cases per million people per year and an overall prevalence of 2.4 to 14 per million adults. There is little knowledge about the genetic factors that influence this disease. There are only two reports of familial EGPA: one in Japan and one in Turkey. We herein report a third case of familial EGPA in a brother and sister who were negative for myeloperoxidase-antineutrophil cytoplasmic antibodies.

Genome-wide association study of eosinophilic granulomatosis with polyangiitis reveals genomic loci stratified by ANCA status

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare inflammatory disease of unknown cause. 30% of patients have anti-neutrophil cytoplasmic antibodies (ANCA) specific for myeloperoxidase (MPO). Here, we describe a genome-wide association study in 676 EGPA cases and 6809 controls, that identifies 4 EGPA-associated loci through conventional case-control analysis, and 4 additional associations through a conditional false discovery rate approach. Many variants are also associated with asthma and six are associated with eosinophil count in the general population. Through Mendelian randomisation, we show that a primary tendency to eosinophilia contributes to EGPA susceptibility. Stratification by ANCA reveals that EGPA comprises two genetically and clinically distinct syndromes. MPO+ ANCA EGPA is an eosinophilic autoimmune disease sharing certain clinical features and an HLA-DQ association with MPO+ ANCA-associated vasculitis, while ANCA-negative EGPA may instead have a mucosal/barrier dysfunction origin. Four candidate genes are targets of therapies in development, supporting their exploration in EGPA.

IgG4:IgG RNA ratio differentiates active disease from remission in granulomatosis with polyangiitis: a new disease activity marker? A cross-sectional and longitudinal study

OBJECTIVES

An important limitation in granulomatosis with polyangiitis (GPA) is the lack of disease activity markers. Immunoglobulin G4-positive (IgG4+) B cells and plasma cells are implicated in the pathogenesis of GPA. We hypothesized that the presence of these cells in peripheral blood could serve as disease activity parameter in GPA.

METHODS

We included 35 proteinase 3-antineutrophil cytoplasmic antibodies-positive patients with GPA in a cross-sectional study. Active disease was defined as Birmingham Vasculitis Activity Score (BVAS) ≥ 3 (n = 15), remission as BVAS of 0 (n = 17), and low disease activity (LDA) as BVAS of 1-2 and clinical remission (n = 3). Healthy subjects (n = 10), patients with systemic lupus erythematosus (n = 24), and patients with rheumatoid arthritis (n = 19) functioned as control subjects. An additional longitudinal study was performed in ten patients with GPA. Using a validated qPCR test, we measured the IgG4:IgG RNA ratio in all groups and compared the results with known biomarkers.

RESULTS

The median qPCR score was higher in active GPA (21.4; IQR 12.1-29.6) than in remission/LDA (3.3; IQR 1.6-5.6) (Mann-Whitney U test, p < 0.0001) and outperformed other known disease activity parameters in detecting activity. A cutoff qPCR score of 11.2% differentiated active disease from remission/LDA accurately (AUC 0.993). The qPCR test correlated well with the BVAS (Spearman r = 0.77, p < 0.0001). In the longitudinal study, a decrease in BVAS correlated with qPCR score reduction (paired t test, p < 0.05).

CONCLUSIONS

The IgG4:IgG RNA ratio in GPA accurately distinguishes active disease from remission and correlates well with disease activity in these single-center studies. If these results are confirmed in larger longitudinal studies, this test might help to steer treatment decisions in patients with GPA.

Circulating CD4+CD8+ double-positive T-cells display features of innate and adaptive immune function in granulomatosis with polyangiitis

OBJECTIVES

To examine functional features of CD4+CD8+ double-positive T-cells in patients with granulomatosis with polyangiitis (GPA) using phenotypic and transcriptomic analysis.

METHODS

Staining of cellular surface marker was performed using freshly collected whole blood. For intracellular cytokine staining freshly collected whole blood was stimulated with phorbol myristate acetate and ionomycin. Multicolor flow cytometric analysis was performed on a FACSCanto II cytometer using FACSDiva software. Lymphocytes were gated on CD3, CD4, and CD8 staining. FACS-sorted CD4+CD8+ double-positive T-cells of GPA-patients and HC (n=3 each) were subjected to transcriptional profiling using an Affymetrix Human Genome 2.0 microarray. Differently expressed genes were analysed using biological databases.

RESULTS

Frequency of CD4+CD8+ double-positive T-cells was increased within the total CD3+ T-cell population in GPA, but no difference was detected between patients with active disease and remission. Percentages of interferon γ (Th1-type), interleukin 17 and interleukin 22 (Th17-type) producing CD4+CD8+ double-positive T-cells exceeded the percentage of interleukin 4 (Th2-type) producing cells. There were no significant differences in the percentages of the respective cytokine-positive CD4+CD8+ double-positive T-cells between GPA and HC. Up-regulated genes of CD4+CD8+ double-positive T-cells in GPA were enriched within Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to nuclear factor kappa-lightchain-enhancer of activated B cells signalling, toll-like receptor signalling, nucleotide-binding oligomerisation domain-like receptor signalling as well as major histocompatibility complex class-II antigen presentation.

CONCLUSIONS

Employing a combined phenotypic and transcriptomic approach we disclosed a Th1/Th17 phenotype as well as innate and adaptive functions of CD4+CD8+ double-positive T-cells in GPA.

SERPINA1 Gene Variants in Granulomatosis with Polyangiitis

Alpha-1 antitrypsin (A1AT) deficiency is one of the most common genetic disorders in Caucasian population. There is a link between granulomatosis with polyangiitis (GPA) and most frequent variants of SERPINA1 gene encoding severe alpha-1 antitripsin deficiency. However, the potential effect of Pi*Z, Pi*S as well as other SERPINA1 variants on clinical course of vasculitis are not well understood. The aim of the study was to analyze the potential effect of A1AT protein phenotype representing the SERPINA1 gene variants on the clinical course of GPA. The study group consisted of 64 subjects with GPA, stratified according to the disease severity: patients in active phase (group I, n = 12), patients during remission on treatment (group II, n = 40) or untreated (group III, n = 12). Normal Pi*MM SERPINA1 genotype was detected by means of real-time polymerase chain reaction (PCR) or direct sequencing in 59 patients, Pi*MZ genotype in 2, and Pi*IM, Pi*MS or Pi*SZ in 1 patient respectively. The patients with abnormal Pi*Z, Pi*S, or Pi*I allele constituted 17% in group I, 5% in group II, and 8% in group III. The serum content of A1AT and high sensitivity C-reactive protein (hsCRP) assessed by nephelometry did not differ between the groups. Interestingly, the mean serum antiPR3-antibodies level detected by Elisa method was significantly greater in the GPA patients with Pi*Z, Pi*S, or Pi*I SERPINA1 variants than in the Pi*MM homozygotes. In summary, heterozygous Pi*MZ, Pi*MS, and Pi*SZ genotype was detected in 7.8% of total group of GPA patients, and in 10.5% of those with lung lesions. The abnormal alleles of Pi*S and Pi*Z may affect the clinical course of the disease.

Rare case of eosinophilic granulomatosis with polyangiitis in two patients with α-1-antitrypsin deficiency (PiSZ)

We present two cases of eosinophilic granulomatosis with polyangiitis occurring with α-1-antitrypsin deficiency, both PiSZ phenotype. The simultaneous occurrence of these two conditions has seldom been described in the literature, despite evidence of an association between α-1-antitrypsin deficiency and other forms of vasculitis. Both patients had pulmonary involvement and reported intermittent exacerbations of vasculitic symptoms. Both patients were managed on low-dose oral steroids and azathioprine remaining well with occasional exacerbations. It is important to consider whether there is an association between eosinophilic granulomatosis with polyangiitis and α-1-antitrypsin deficiency, as this may lead to more severe pulmonary symptoms during exacerbations. If a genetic association between the two conditions is found, clinicians should be aware of the possible need to screen for α-1-antitrypsin deficiency in appropriate patients.

Orbital pseudotumor can be a localized form of granulomatosis with polyangiitis as revealed by gene expression profiling

Biopsies and ANCA testing for limited forms of granulomatosis with polyangiitis (GPA) are frequently non-diagnostic. We characterized gene expression in GPA and other causes of orbital inflammation. We tested the hypothesis that a sub-set of patients with non-specific orbital inflammation (NSOI, also known as pseudotumor) mimics a limited form of GPA. Formalin-fixed, paraffin-embedded orbital biopsies were obtained from controls (n=20) and patients with GPA (n=6), NSOI (n=25), sarcoidosis (n=7), or thyroid eye disease (TED) (n=20) and were divided into discovery and validation sets. Transcripts in the tissues were quantified using Affymetrix U133 Plus 2.0 microarrays. Distinct gene expression profiles for controls and subjects with GPA, TED, or sarcoidosis were evident by principal coordinate analyses. Compared with healthy controls, 285 probe sets had elevated signals in subjects with GPA and 1472 were decreased (>1.5-fold difference, false discovery rate adjusted p<0.05). The immunoglobulin family of genes had the most dramatic increase in expression. Although gene expression in GPA could be readily distinguished from gene expression in TED, sarcoidosis, or controls, a comparison of gene expression in GPA versus NSOI found no statistically significant differences. Thus, forms of orbital inflammation can be distinguished based on gene expression. NSOI/pseudotumor is heterogeneous but often may be an unrecognized, localized form of GPA.

Association of granulomatosis with polyangiitis (Wegener's) with HLA-DPB1*04 and SEMA6A gene variants: evidence from genome-wide analysis

OBJECTIVE

To identify genetic determinants of granulomatosis with polyangiitis (Wegener's) (GPA).

METHODS

We carried out a genome-wide association study (GWAS) of 492 GPA cases and 1,506 healthy controls (white subjects of European descent), followed by replication analysis of the most strongly associated signals in an independent cohort of 528 GPA cases and 1,228 controls.

RESULTS

Genome-wide significant associations were identified in 32 single-nucleotide polymorphic (SNP) markers across the HLA region, the majority of which were located in the HLA-DPB1 and HLA-DPA1 genes encoding the class II major histocompatibility complex (MHC) DPβ chain 1 and DPα chain 1 proteins, respectively. Peak association signals in these 2 genes, emanating from SNPs rs9277554 (for DPβ chain 1) and rs9277341 (DPα chain 1) were strongly replicated in an independent cohort (in the combined analysis of the initial cohort and the replication cohort, P = 1.92 × 10(-50) and 2.18 × 10(-39) , respectively). Imputation of classic HLA alleles and conditional analyses revealed that the SNP association signal was fully accounted for by the classic HLA-DPB1*04 allele. An independent single SNP, rs26595, near SEMA6A (the gene for semaphorin 6A) on chromosome 5, was also associated with GPA, reaching genome-wide significance in a combined analysis of the GWAS and replication cohorts (P = 2.09 × 10(-8) ).

CONCLUSION

We identified the SEMA6A and HLA-DP loci as significant contributors to risk for GPA, with the HLA-DPB1*04 allele almost completely accounting for the MHC association. These two associations confirm the critical role of immunogenetic factors in the development of GPA.

Incidence of alpha-1 antitrypsin Z and S alleles in patients with granulomatosis with polyangiitis--pilot study

INTRODUCTION

Inherited alpha-1 antitrypsin (AAT) deficiency is one of the three most common genetic disorders in Caucasians. It considerably increases the risk of progressive obstructive lung diseases, mostly chronic obstructive pulmonary disease. It has also been suggested that AAT deficiency might be instrumental vasculitis associated with the anti-neutrophil cytoplasm antibodies (cANCA) and subsequent lung tissue injury.

MATERIAL AND METHODS

We present the results from a pilot study involving 51 patients with granulomatosis with polyangiitis, formerly known as Wegener's granulomatosis (GPA), 43 of whom were cANCA positive. The control group consisted of 658 individuals. AAT blood concentration assessment by nephelometry, phenotyping by isoelectrofocusing and real-time PCR genotyping were performed.

RESULTS

Deficiency alleles PI*Z and PI*S were detected in 3 (5.88%) and in 2 patients (3.92%) with GPA, respectively. All of them were cANCA positive. In the controls, PI*Z was observed in 2.8% while PI*S in 1.5% of cases. Accordingly, the increased incidence of main deficiency alleles was demonstrated in GPA, and particularly in cANCA+GPA patients, when compared to the controls. The estimated frequency for PI*Z in GPA, cANCA+GPA patients and controls was, respectively, 29.4/1000, 34.9/1000 and 13.7/1000, whereas for PI*S it was 19.2/1000, 23.2/10,00 and 7.6/1000. However, the observed differences did not reach statistical significance due to the considerable size disproportion between groups. CONSCLUSIONS: We believe that our preliminary data confirm the clinical importance of AAT deficiency in GPA patients and the need to screen for AAT deficiency alleles. The study is on-going.

Genetically distinct subsets within ANCA-associated vasculitis

BACKGROUND

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a severe condition encompassing two major syndromes: granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis) and microscopic polyangiitis. Its cause is unknown, and there is debate about whether it is a single disease entity and what role ANCA plays in its pathogenesis. We investigated its genetic basis.

METHODS

A genomewide association study was performed in a discovery cohort of 1233 U.K. patients with ANCA-associated vasculitis and 5884 controls and was replicated in 1454 Northern European case patients and 1666 controls. Quality control, population stratification, and statistical analyses were performed according to standard criteria.

RESULTS

We found both major-histocompatibility-complex (MHC) and non-MHC associations with ANCA-associated vasculitis and also that granulomatosis with polyangiitis and microscopic polyangiitis were genetically distinct. The strongest genetic associations were with the antigenic specificity of ANCA, not with the clinical syndrome. Anti-proteinase 3 ANCA was associated with HLA-DP and the genes encoding α(1)-antitrypsin (SERPINA1) and proteinase 3 (PRTN3) (P=6.2×10(-89), P=5.6×10(-12,) and P=2.6×10(-7), respectively). Anti-myeloperoxidase ANCA was associated with HLA-DQ (P=2.1×10(-8)).

CONCLUSIONS

This study confirms that the pathogenesis of ANCA-associated vasculitis has a genetic component, shows genetic distinctions between granulomatosis with polyangiitis and microscopic polyangiitis that are associated with ANCA specificity, and suggests that the response against the autoantigen proteinase 3 is a central pathogenic feature of proteinase 3 ANCA-associated vasculitis. These data provide preliminary support for the concept that proteinase 3 ANCA-associated vasculitis and myeloperoxidase ANCA-associated vasculitis are distinct autoimmune syndromes. (Funded by the British Heart Foundation and others.).

Expression profile of proinflammatory genes in neutrophil-enriched granulocytes stimulated with native anti-PR3 autoantibodies

Granulomatosis with polyangiitis (Wegener's ) is a rare autoimmune disease associated with the presence of antibodies directed against neutrophil antigen, proteinase-3 (PR3). The mechanisms by which anti-neutrophil cytoplasmic antibodies (ANCA) may activate neutrophils are still not well understood. In the present study we analyzed neutrophil gene expression profile after anti-PR3 antibodies stimulation. Briefly neutrophils isolated from 12 healthy volunteers, who tested negative for anti-PR3 autoantibodies, were stimulated with anti-PR3 IgG and activation of 147 genes was analyzed with the use of TaqMan low-density arrays. In stimulated neutrophils we observed up-regulation of 13 genes (CCL2, CXCL2, VCAM1, MMP9, PLCB4, PDE4C, PLA2G4C, RAC1, RHOA, IRAK1, CACNA1D, CACNB2, PTGDR), further 11 genes were up-regulated only in some donors (IL13, PF4, IL2RG, ITGB1, CD83, PLA2G7, ALOX12, AXNA1, AXNA5, LTA4H, MCR2) yet two others (HRH3 and PLA2G2D) were up-regulated in a few samples and undetectable in others. The obtained results demonstrate that c-ANCA mediated activation of neutrophils involve several pathways mediated via FcγRs like calcium signaling, phosphatidylinositol 3-kinase AKT pathway or MAPK signaling systems, but also inducts others, like G-protein signaling. Neutrophil is a very sensitive cell, responding to many environment changes. As our results showed, some anti-PR3 responses are highly variable across donors. Perhaps, this variablity also contribute to the susceptibility for granulocyte vasculitis and requires future studies.

Histopathology of aseptic necrosis of the femoral head in sickle cell disease

This study compares the histopathology of bone biopsies from patients suffering from sickle cell anaemia (homozygote SS) to heterozygote patients (SA) and homozygotes with aseptic osteonecrosis (AA). The sensitivity to bacterial infection of sickle cell patients raises the question of the aetiology of sepsis in the onset of the necrosis. To our knowledge this study is the first to analyse the histopathology of osteonecrosis of the femoral head, at its early stages, in sickle cell anaemia. At the University Hospital of Pointe-à-Pitre, from 1994 to 2007, 38 bone biopsies were obtained from adult patients with avascular necrosis of the femoral head at the time of a core decompression procedure (SS, SC: 27; AS: 5; AA: 6). The histology of the biopsies confirmed the necrosis; all bacteriological cultures were negative. Patients displaying one S gene (SS, SC, AS) compared to homozygote subjects (AA) showed a significant increase of a nonspecific inflammatory granulomatosis (p = 0.003). No relationship was observed between the radiological stages and the histology whatever the genotype (p = 0.1). Inflammatory histopathology without sepsis or advanced alteration characterises the early stages of sickle cell necrosis. This inflammatory process is absent in idiopathic avascular necrosis.

Transcription of proteinase 3 and related myelopoiesis genes in peripheral blood mononuclear cells of patients with active Wegener's granulomatosis

OBJECTIVE

Wegener's granulomatosis (WG) is a systemic inflammatory disease that is associated with substantial morbidity. The aim of this study was to understand the biology underlying WG and to discover markers of disease activity that would be useful for prognosis and treatment guidance.

METHODS

Gene expression profiling was performed using total RNA from peripheral blood mononuclear cells (PBMCs) and granulocyte fractions from 41 patients with WG and 23 healthy control subjects. Gene set enrichment analysis (GSEA) was performed to search for candidate WG-associated molecular pathways and disease activity biomarkers. Principal components analysis was used to visualize relationships between subgroups of WG patients and controls. Longitudinal changes in proteinase 3 (PR3) gene expression were evaluated using reverse transcription-polymerase chain reaction, and clinical outcomes, including remission status and disease activity, were determined using the Birmingham Vasculitis Activity Score for WG (BVAS-WG).

RESULTS

Eighty-six genes in WG PBMCs and 40 in WG polymorphonuclear neutrophils (PMNs) were significantly up-regulated relative to controls. Genes up-regulated in WG PBMCs were involved in myeloid differentiation, and these included the WG autoantigen PR3. The coordinated regulation of myeloid differentiation genes was confirmed by GSEA. The median expression values of the 86 up-regulated genes in WG PBMCs were associated with disease activity (P = 1.3 x 10(-4)), and WG patients with low-level expression of the WG signature genes showed expression profiles that were only modestly different from that in healthy controls (P = 0.07). PR3 transcription was significantly up-regulated in WG PBMCs (P = 1.3 x 10(-5), false discovery rate [FDR] 0.002), but not in WG PMNs (P = 0.03, FDR 0.28), and a preliminary longitudinal analysis showed that the fold change in PR3 RNA levels in WG PBMCs corresponded to changes in the BVAS-WG score over time.

CONCLUSION

Transcription of PR3 and related myeloid differentiation genes in PBMCs may represent novel markers of disease activity in WG.

A functionally relevant IRF5 haplotype is associated with reduced risk to Wegener's granulomatosis

Wegener's granulomatosis (WG), characterized by systemic vasculitis and granulomatous inflammation, is a rare chronic rheumatic condition potentially sharing some etiopathological principles with other autoimmune disorders, e.g., rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Several large association studies have identified genetic risk factors for RA and SLE. Thereof, we have evaluated the relevance of the most promising ones in WG. 22 single nucleotide polymorphisms (SNPs) within or in the vicinity of CCL21, CD40, CDK6, IL21, IL2RB, IRF5, KIF5A, KLF12, MMEL1, PRKCQ, STAT4, TNFAIP3, and TRAF1/C5 have been genotyped in >600 German WG cases and >800 matched controls. While most polymorphisms did not show suspicious effects on WG susceptibility, SNPs representing TNFAIP3 (rs6922466, p = 0.032, odds ratio (OR) 0.83, 95% confidence interval (CI) 0.7--0.98) and CDK6 (rs42041, p = 0.0201, OR 1.21, 95% CI 1.03-1.43) revealed nominally significant differences in allele distribution. The strongest association was detected for a functionally relevant four SNP haplotype of IRF5, which comprised a protective effect (p = 0.0000897, p (corrected) = 0.0012, OR 0.73, 95% CI 0.62-0.85) similar to those previously seen in RA and SLE. Thus, we suggest that WG, SLE, and RA share some, but not many, genetic risk factors, which supports models of partly overlapping etiopathological mechanisms in these disorders.

Genetic associations of variants of the high affinity receptor for immunoglobulin E in Wegener's granulomatosis

Immunoglobulin E (IgE) and the high affinity IgE receptor (FcepsilonRI) have been suggested to contribute to the pathogenesis of autoimmune disorders. Their role in Wegener's granulomatosis (WG) are, however, poorly recognized. We sought a genetic association between laboratory markers for the disease, i.e. anti-proteinase 3 antibodies (anti-PR3), anti-myeloperoxidase antibodies, anti-cyclic citrullinated peptide antibodies, C-reactive protein (CRP), C3c and C4 complement components, and total serum IgE levels in WG subjects with common genetic variants of FcepsilonRI subunits. Anti-PR3 and CRP and serum IgE levels showed significant associations, while complement components tended to be associated, with -18483A > C and/or -344C > T FCER1A (FcepsilonRI alpha-subunit gene) polymorphisms. Moreover, a correlation between -109T > C FCER1B (FcepsilonRI beta-subunit gene) genotypes and serum IgE was observed. Both WG specific auto-antibodies and other blood inflammatory markers displayed correlations with serum total IgE levels and genetic variants of the high affinity receptor for this immunoglobulin. This observation suggests a functional relantionship of FcepsilonRI in the regulation of autoimmune response observed in WG.

The p53 G72C and MDM2 T309G single nucleotide polymorphisms in patients with Wegener's granulomatosis

OBJECTIVE

Wegener's granulomatosis (WG) is a rare disease with unknown aetiology, but there is evidence for a complex genetic background. The tumor suppressor p53 and its most important negative regulator, MDM2, are positioned in the centre of a pathway that eliminates damaged cells through apoptosis. Furthermore, p53 is one of the most important negative regulators of the pro-inflammatory transcription factor nuclear factor kappa b (NFkappaB). In this respect the investigation of polymorphisms in the p53-network could be a promising approach contributing susceptibility of WG and its course of disease.

METHODS

A case control study with 132 patients with WG and 512 healthy blood donors was conducted to evaluate an association of p53-SNP G72C or MDM2-SNP T309G with WG. SNPs were genotyped by polymerase chain reaction (PCR) and subsequent differential enzymatic restriction. All patients showed the clinical pathological findings of WG according to the ACR classification criteria of 1990.

RESULTS

The p53 G72C and MDM2 T309G polymorphisms did not show any difference between WG patients and controls. The subgroup analysis of gender differences and earlier onset of WG (younger than median age of 51 years at diagnosis) did not show any differences in allelic or genotype frequencies of p53 G72C or MDM2 T309G SNP between WG patients and the control group.

CONCLUSIONS

Our study showed no association between the p53 SNP G72C and the MDM2 SNP T309G with susceptibility or course of disease in patients with WG. The data presented do not suggest that alterations in the p53-network play a key role in the pathogenesis of WG.

[B lymphocyte differentiation in granulomatous tissues of the lung and the nasal mucosa in Wegener's granulomatosis: origin of anti-neutrophil cytoplasmic antibody formation?]

Wegener's granulomatosis (WG) starts with granulomatous inflammation of the respiratory tract before it converts into a potentially organ and life threatening systemic vasculitis associated with anti-neutrophil cytoplasmic antibodies (ANCA). The site of formation of the highly specific ANCA directed against "Wegener's autoantigen" proteinase 3 (PR3) is still unknown. Previously, we have shown that follicle-like B lymphocytic infiltrates in the vicinity to PR3 expressing cells in WG-granulomata. We characterized the immunoglobulin-VH repertoire in lung and nasal granulomata (paraffin embedded) from four WG patients. A total of 115 individual VH genes were characterized and compared to 84 VH genes from the peripheral blood of a healthy donor. We found an increased frequency of mutations with a bias to amino acid exchanges within the antigen binding sites (CDR) 1 and 2 in WG tissue. A large number of mutations led to negatively charged amino acids and may increase affinity to the positively charged PR3. Furthermore, the occurrence of differently mutated members of one B cell clone indicates clonal expansion and intraclonal diversification by an antigen, e.g. PR3. Several WG tissue derived genes displayed similarities to published sequences from peripheral PR3 ANCA producing B cells. Thus, granulomata of the lower and upper respiratory tract contain follicle-like B cell clusters with a selected VH repertoire infiltrate in WG. WG granulomata could be the place of autoantigen presentation and formation of high-affinity ANCA within neoformed ectopic or tertiary lymphoid-like tissue areas.

The frequency of anticardiolipin antibodies and genetic mutations associated with hypercoagulability among patients with Wegener's granulomatosis with and without history of a thrombotic event

OBJECTIVE

Venous thrombotic events (VTE), including both deep venous thrombosis and pulmonary emboli, are now recognized as an important complication of Wegener's granulomatosis (WG), but the mechanism(s) of this occurrence is unclear. The frequency of anticardiolipin antibodies (aCL), anti-beta2-glycoprotein antibodies (anti-beta2-GP), and several genetic hypercoagulable factors were examined in a large cohort of patients with WG.

METHODS

One hundred eighty patients with active WG had serum and DNA samples collected upon entry into a clinical trial. Of the 180 patients, 29 patients had VTE -- 13 before trial entry, 16 during trial. aCL (IgG, IgM, and IgA) and anti-beta2-GP (IgG and IgM) were evaluated in 176 patients. Factor V Leiden (FVL), the prothrombin gene mutation (G20210A, PGM), and methylenetetrahydrofolate reductase (MTHFR) gene mutation were tested in the 29 patients with thrombotic events, and 36 patients without.

RESULTS

aCL occurred with increased frequencies in patients with WG when compared to the general population (1%-5%): 12% had aCL and 3% had anti-beta2-GP. There was no difference in the prevalences of aCL or anti-beta2-GP based on clotting status. The prevalence of the genetic hypercoagulable factors examined in patients with WG was comparable to the reported rates in the general population.

CONCLUSION

Although the incidence of clinically significant VTE is increased in patients with WG, this increased risk is not explained by increased prevalences of aCL, anti-beta2-GP, FVL, or mutations in PGM or MTHFR. These observations suggest a need to search for new genetic or acquired prothrombotic abnormalities to account for the increased thrombotic event rate in patients with active WG.

Proteinase 3, the Wegener autoantigen, is externalized during neutrophil apoptosis: evidence for a functional association with phospholipid scramblase 1 and interference with macrophage phagocytosis

Proteinase 3 (PR3), a serine proteinase contained in neutrophil azurophilic granules, is considered a risk factor for vasculitides and rheumatoid arthritis when expressed on the outer leaflet of neutrophil plasma membrane and is the preferred target of antineutrophil cytoplasm autoantibodies (ANCA) in Wegener granulomatosis. ANCA binding to PR3 expressed at the surface of neutrophils activates them. Evidence is provided that neutrophil apoptosis induced significantly more membrane PR3 expression without degranulation (but no enhanced membrane CD35, CD66b, CD63, myeloperoxidase, or elastase expression). This observation was confirmed on cytoplasts, a model of granule-free neutrophils. We hypothesized that PR3 could interact with proteins involved in membrane flip-flop (eg, phospholipid scramblase 1 [PLSCR1]). PR3-PLSCR1 interaction in neutrophils was demonstrated by confocal microscopy and coimmunoprecipitation. In the RBL-2H3 rat mast-cell line stably transfected with PR3 or its inactive mutant (PR3S203A), PR3 externalization depended on PLSCR1, as shown by less PR3 externalization in the presence of rPLSCR1 siRNA, but independently of its serine-proteinase activity. Finally, apoptosis-externalized PR3 decreased the human macrophage-phagocytosis rate of apoptotic PR3 transfectants. Therefore, in addition to ANCA binding in vasculitis, the proinflammatory role of membrane PR3 expression may involve interference with macrophage clearance of apoptotic neutrophils.

FCGR3B copy number variation is associated with susceptibility to systemic, but not organ-specific, autoimmunity

Naturally occurring variation in gene copy number is increasingly recognized as a heritable source of susceptibility to genetically complex diseases. Here we report strong association between FCGR3B copy number and risk of systemic lupus erythematosus (P = 2.7 x 10(-8)), microscopic polyangiitis (P = 2.9 x 10(-4)) and Wegener's granulomatosis in two independent cohorts from the UK (P = 3 x 10(-3)) and France (P = 1.1 x 10(-4)). We did not observe this association in the organ-specific Graves' disease or Addison's disease. Our findings suggest that low FCGR3B copy number, and in particular complete FCGR3B deficiency, has a key role in the development of systemic autoimmunity.

Mannose-binding lectin gene polymorphisms in a cohort study of ANCA-associated small vessel vasculitis

OBJECTIVE

To investigate whether single nucleotide polymorphisms (SNPs) within the mannose-binding lectin (MBL) gene are associated with small vessel vasculitis (SVV) and are a risk factor for intercurrent infection, as described previously in other autoimmune diseases.

METHODS

Six SNPs in the MBL promoter and coding region were genotyped by sequence-specific polymerase chain reaction or restriction fragment length polymorphism assay in 170 white Caucasians with SVV and 372 ethnically matched controls in a case-control association study. Serum MBL levels were measured by ELISA. The genotype and protein concentrations were correlated to clinical details retrieved from hospital records.

RESULTS

No differences in allelic and genotypic frequencies were detected between patients with SVV and control subjects. MBL deficiency did not increase the susceptibility to infection (P = 0.6, Fisher's exact test) or the duration of hospital stay.

CONCLUSION

Our data suggest that MBL polymorphisms are not associated with SVV and do not influence the incidence of concomitant infections. These results raise doubts about the usefulness of MBL polymorphisms as a predictive marker for infection in SVV.

Granulomatose de Wegener

Wegener's granulomatosis is described by the Chapel Hill nomenclature (1994) as a systemic necrotizing vasculitis affecting small to medium-sized vessels. Cytoplasm-labeling antineutrophil cytoplasmic autoantibodies (cANCA) directed against proteinase 3 (PR3) are detected in the sera of approximately 90% of patients. Reported incidence varies from 2 to 12 cases/million inhabitants/year and prevalence from 24 to 157 cases/million inhabitants, depending on the series. While still rare, incidence seems to have increased slightly over the past few decades. Most new cases involve adults aged 45-60 years. Many of the immune mechanisms involved in its pathogenesis have been identified. These involve cANCA as well as neutrophils, various lymphocyte subtypes, activation molecules, and cytokines. Genetic and environmental factors have been observed in some cases. However, the precise causes of the disease and of the initial immune process leading to cANCA production remain unknown. The most characteristic clinical manifestations are involvement of the upper and lower respiratory tracts and glomerulonephritis. Diffuse/systemic forms may be clinically distinguished from localized/limited forms: the former are mainly associated with vasculitis, and the latter with granulomatous inflammation. Diagnosis relies largely on the combination of characteristic clinical symptoms and cANCA anti-PR3, but histological confirmation should always be obtained when biopsy of affected organs is feasible and safe. Kidney biopsy is particularly useful in cases with renal manifestations, because it also provides some prognostic information. Current recommendations for treatment of systemic forms call first for an induction phase that combines corticosteroids and intravenous cyclophosphamide; the first three pulses are given every 2 weeks and then every 3 weeks until remission is achieved, followed by a maintenance phase with a less toxic immunosuppressant. The optimal duration of this regimen has not yet been determined, but it must certainly not be less than 18 months. Continuation of cotrimoxazole for two additional years is advised once immunosuppressants have been withdrawn. Remission is obtained in more than 85% of the cases to date, but the high relapse rate remains a matter of concern: approximately half of all patients will relapse within the five years following diagnosis. Promising new therapeutic agents, including rituximab, anti-TNF-alpha, and abatacept, are currently under evaluation and may substantially modify management of this disease in the years to come. Today, however, they are reserved for refractory cases.

Major histocompatibility complex HLA region largely explains the genetic variance exercised on neutrophil membrane proteinase 3 expression

ANCA-associated vasculitides, a common cause of rapidly progressive glomerulonephritis, are influenced by genetic variance. Neutrophil membrane expression of the ANCA antigen proteinase 3 (PR3) is pathogenically important. A subset of membrane PR3-positive neutrophils can be distinguished from a membrane-negative subset in any given subject. The percentage of membrane PR3-positive neutrophils is genetically determined. In this study, 17 pairs of HLA-matched siblings were typed for their percentage of membrane PR3-positive neutrophils. The HLA-matched siblings showed a high concordance (r = 0.67, P < 0.05), similar to that seen in monozygotic twins. For testing of whether the HLA system influences membrane PR3 percentage, membrane PR3 typing and HLA typing of 51 unrelated patients with Wegener's granulomatosis and 49 normal control subjects was performed. Using two independent statistical methods, a group of 34 HLA antigens was found to predict a large fraction of the membrane PR3 phenotype in patients and control subjects. Certain major histocompatibility HLA antigens have been implicated to conflicting degrees in ANCA-associated vasculitides. However, in earlier studies, the contribution of the HLA system to the genetic variance of the disease was unclear. In this cohort, found was an association of Wegener's granulomatosis with the same group of HLA antigens that predicted for membrane PR3 percentage and a similar correlation with clinical parameters at initial presentation. The disease status in 80% of the patients and 82% of the control subjects could be predicted correctly on the basis of HLA typing by discriminate function analysis (P < 0.001). After removal of the predicted individual from the sample, this association remained significant (64 and 63% correct prediction; P < 0.001). The data suggest that a complex interaction of the entire HLA system is responsible for the genetic influence on membrane PR3 percentage and Wegener's granulomatosis.

On the Wegener granulomatosis associated region on chromosome 6p21.3

BACKGROUND

Wegener granulomatosis (WG) belongs to the heterogeneous group of systemic vasculitides. The multifactorial pathophysiology of WG is supposedly caused by yet unknown environmental influence(s) on the basis of genetic predisposition. The presence of anti-neutrophil cytoplasmic antibodies (ANCA) in the plasma of patients and genetic involvement of the human leukocyte antigen system reflect an autoimmune background of the disease. Strong associations were revealed with WG by markers located in the major histocompatibility complex class II (MHC II) region in the vicinity of human leukocyte antigen (HLA)-DPB1 and the retinoid X receptor B (RXRB) loci. In order to define the involvement of the 6p21.3 region in WG in more detail this previous population-based association study was expanded here to the respective 3.6 megabase encompassing this region on chromosome 6. The RXRB gene was analysed as well as a splice-site variation of the butyrophilin-like (BTNL2) gene which is also located within the respective region. The latter polymorphism has been evaluated here as it appears as a HLA independent susceptibility factor in another granulomatous disorder, sarcoidosis.

METHODS

150-180 German WG patients and a corresponding cohort of healthy controls (n = 100-261) were used in a two-step study. A panel of 94 microsatellites was designed for the initial step using a DNA pooling approach. Markers with significantly differing allele frequencies between patient and control pools were individually genotyped. The RXRB gene was analysed for single strand conformation polymorphisms (SSCP) and restriction fragment length polymorphisms (RFLP). The splice-site polymorphism in the BTNL2 gene was also investigated by RFLP analysis.

RESULTS

A previously investigated microsatellite (#1.0.3.7, Santa Cruz genome browser (UCSC) May 2004 Freeze localisation: chr6:31257596-34999883), which was used as a positive control, remained associated throughout the whole two-step approach. Yet, no additional evidence for association of other microsatellite markers was found in the entire investigated region. Analysis of the RXRB gene located in the WG associated region revealed associations of two variations (rs10548957 pallelic = 0.02 and rs6531 pallelic = 5.20 x 10-5, OR = 1.88). Several alleles of markers located between HLA-DPB1, SNP rs6531 and microsatellite 1.0.3.7 showed linkage disequilibrium with r2 values exceeding 0.10. Significant differences were not demonstrable for the sarcoidosis associated splice-site variation (rs2076530 pallelic = 0.80) in our WG cohort.

CONCLUSION

Since a microsatellite flanking the RXRB gene and two intragenic polymorphisms are associated significantly with WG on chromosome 6p21.3, further investigations should be focussed on extensive fine-mapping in this region by densely mapping with additional markers such as SNPs. This strategy may reveal even deeper insights into the genetic contributions of the respective region for the pathogenesis of WG.

Epidemiology of Wegener's granulomatosis: Lessons from descriptive studies and analyses of genetic and environmental risk determinants

During the past 15 years, the epidemiology of Wegener's granulomatosis (WG) has become better understood. Descriptive epidemiological studies carried out primarily in European countries estimate a prevalence of WG ranging from 24 to 157 per million and annual incidence rates from 3 to 14 per million. These studies suggest a North-South declining gradient in disease risk in the Northern Hemisphere and an increase in incidence over time, although the latter is likely largely due to improved diagnostic ascertainment. Data also indicate the presence of potential secular and seasonal variations in WG incidence and a decreasing disease risk among non-Caucasians. Furthermore, analytic epidemiological studies have pointed out putative genetic and non-genetic risk factors for WG. Genetic investigations have identified various candidate genes, with alpha1-antitrypsin deficiency being the most consistently reported genetic susceptibility factor to date. Even though much less research has been devoted to environmental risk factors, evidence has grown for a possible relationship between WG and occupational exposure to crystalline silica. Thus far, data support the concept of WG as a multifactorial disease in which genetic and environmental determinants are involved but a major gap in understanding persists regarding the extent to which both factors contribute to its development. This and many other questions remain to be answered by future structured epidemiological research. This review focuses on the current knowledge of descriptive epidemiology and genetic and environmental factors associated with WG.

Promoter polymorphism rs3087456 in the MHC class II transactivator gene is not associated with susceptibility for selected autoimmune diseases in German patient groups

We analysed whether the single nucleotide polymorphism (SNP) rs3087456 in the promoter of the MHC class II transactivator (MHC2TA) gene is associated with manifestation of rheumatoid arthritis, multiple sclerosis, narcolepsy and Wegener granulomatosis. The recently reported association in a northern population of the MHC2TA variation with these autoimmune diseases is not evident in the German population.

Analysis of a biomarker for Wegener's granulomatosis

Summary This molecular epidemiology study integrated questionnaire and genotype information to examine a disease susceptibility hypothesis. The study was based on a previously reported association demonstrated between a single nucleotide polymorphism (SNP) identified as A-564G within the promoter of the proteinase-3 gene (PRTN3) and the autoimmune disease Wegener's granulomatosis (WG). To further examine the strength of this association, we employed a family-based design in which the inheritance of alternate alleles could be ascertained from the parents of affected and unaffected progeny. Genotype information for the study participants was derived from DNA samples from participants who collected buccal cells using a harvesting method that was non-invasive and self-administered. A brief questionnaire captured demographic data on the participants, the family relationships between participants, and the prevalence of autoimmune disease among family members. Samples were obtained on 132 individuals representing 43 WG cases and 89 unaffected controls. Thirty-four nuclear families containing at least one unaffected sibling or parent of a WG case were represented in this sample. We found no evidence for an association between A-564G and the likelihood of a WG diagnosis. We examined five additional SNPs and a sixth SNP haplotype within the PRTN3 promoter region in a family-based association analysis and found no evidence that mutations within PRTN3 are associated with WG diagnosis.

Distinct tumour necrosis factor alpha, interferon gamma, interleukin 10, and cytotoxic T cell antigen 4 gene polymorphisms in disease occurrence and end stage renal disease in Wegener's granulomatosis

BACKGROUND

Cytokines and T cell regulatory proteins play an important role in the pathogenesis of Wegener's granulomatosis (WG).

OBJECTIVE

To investigate cytokine and cytotoxic T cell antigen-4 (CTLA4) gene polymorphisms and HLA class II alleles in generalised WG.

METHODS

The distribution of cytokine and cytotoxic T cell antigen 4 (CTLA4) gene polymorphisms and HLA class II alleles was analysed in 32 patients with generalised WG and 91 healthy controls. Genotyping was carried out for HLA-DRB1 and HLA-DQB1 and for polymorphism of the genes encoding TNF alpha (-238, -308, -376), TGF beta (codon 10 and 25), IFN gamma (+874), IL6 (-174), IL10 (-592, -819, -1082), CTLA4 (-318, +49), and the (AT)(n) repeats of the CTLA4 gene. In addition, stratification analysis was carried out according to the presence (n = 15) or absence (n = 17) of end stage renal disease.

RESULTS

An increase in the IFN gamma +874 T/T (odds ratio (OR) = 3.14) and TNF alpha -238 G/A (OR = 5.01) genotypes was found in WG patients. When ESRD positive and negative patients were compared, the IFN gamma +874 A/A and the CTLA4 -318 C/C genotypes were found more often in the ESRD subgroup (OR = 10.6 and OR = 2.25). WG patients without ESRD had a higher frequency of the IL10 GCC/ACC promotor genotype (OR = 0.13) and long CTLA4 (AT)(n) repeats (OR = 0.4). No effect was seen for HLA-DR and -DQ markers.

CONCLUSIONS

Disease susceptibility and clinical course in WG may be associated with distinct polymorphisms of cytokine and CTLA4 genes.

Association study with Wegener granulomatosis of the human phospholipase Cgamma2 gene

Background

Wegener Granulomatosis (WG) is a multifactorial disease of yet unknown aetiology characterized by granulomata of the respiratory tract and systemic necrotizing vasculitis. Analyses of candidate genes revealed several associations, e.g. with α(1)-antitrypsin, proteinase 3 and with the HLA-DPB1 locus. A mutation in the abnormal limb mutant 5 (ALI5) mouse in the region coding for the hydrophobic ridge loop 3 (HRL3) of the phospholipaseCγ2 (PLCγ-2) gene, corresponding to human PLCγ-2 exon 27, leads to acute and chronic inflammation and granulomatosis. For that reason, we screened exons 11, 12 and 13 coding for the hydrophobic ridge loop 1 and 2 (HRL1 and 2, respectively) and exon 27 of the PLCγ-2 protein by single strand conformation polymorphism (SSCP), sequencing and PCR/ restriction fragment length polymorphism (RFLP) analyses. In addition, we screened indirectly for disease association via 4 microsatellites with pooled DNA in the PLCγ-2 gene.

Results

Although a few polymorphisms in these distinct exons were observed, significant differences in allele frequencies were not identified between WG patients and respective controls. In addition, the microsatellite analyses did not reveal a significant difference between our patient and control cohort.

Conclusion

This report does not reveal any hints for an involvement of the PLCγ-2 gene in the pathogenesis of WG in our case-control study.

Association study of Wegener granulomatosis and the functionally relevant A645G polymorphism in the bactericidal/permeability increasing protein (BPI) gene

In antineutrophil cytoplasmatic antibody (ANCA)-associated vasculitides (AAV), bactericidal/permeability increasing protein (BPI) ANCAs are detected. Recent observations suggest that BPI-ANCAs can potentially contribute to a proinflammatory setting in the absence of proteinase 3 (PRTN3) ANCAs during the development of a pulmonary relapse by impeding the elimination of Gram-negative bacteria (GNB). However, it is as yet not clear whether the genetic background contributes to the generation of BPI-ANCAs in Wegener granulomatosis (WG) or if BPI polymorphisms are associated with WG. In this study we genotyped the functionally relevant single nucleotide polymorphism (SNP) A645 (Glu216Lys) of the BPI gene in 201 WG patients and 608 healthy controls. To investigate whether further SNPs might be associated with WG, we also examined an intragenic microsatellite marker. No significant differences were found between patients and controls. Thus BPI polymorphisms do not appear to contribute to genetic predisposition to WG. Moreover, our data do not suggest a genetic background for the generation of BPI-ANCAs in WG.

ThePTPN22 620W allele is a risk factor for Wegener's granulomatosis

OBJECTIVE

Analyses of families with multiple autoimmune disorders have revealed a functional polymorphism, 620W, in the intracellular tyrosine phosphatase gene PTPN22 as a predisposing factor for type 1 diabetes, seropositive rheumatoid arthritis, systemic lupus erythematosus, and Hashimoto thyroiditis, and the presence of the PTPN22 protein appears to herald the development of autoantibodies in these disorders. This study therefore examined whether the functionally relevant PTPN22 polymorphism is associated with Wegener's granulomatosis (WG).

METHODS

A population-based study was performed for the PTPN22 polymorphism in 199 patients with WG and in 399 healthy individuals. The R620W variation was investigated by simple restriction fragment-length polymorphism analysis.

RESULTS

The PTPN22 620W allele frequency was significantly increased in antineutrophil cytoplasmic antibody (ANCA)-positive WG patients compared with healthy controls (P < 0.001). The association was particularly striking in patients with kidney, lung, eye, and peripheral nervous system involvement (i.e., those with generalized WG).

CONCLUSION

The PTPN22 620W allele appears to be involved in the pathogenesis of WG, and ANCA positivity seems to be the hallmark.

Complex genetics of Wegener granulomatosis

Wegener granulomatosis (WG) belongs to a heterogeneous group of systemic anti-neutrophil cytoplasmatic antibody (ANCA) associated vasculitides (AASV). WG is characterized by necrotizing granulomatous inflammation of the upper and lower respiratory tract, glomerulonephritis and vasculitis. As a multifactorial model disease, WG is hallmarked by the presence of specific ANCA-subtypes directed against a defined antigen. WG is more predominant among Caucasians and the genetic predisposition appears quite complex. Here, we provide a brief overview concerning genetic factors in the pathogenesis of WG and discuss intricacies of molecular genetic approaches.

The - 564 A/G polymorphism in the promoter region of the proteinase 3 gene associated with Wegener's granulomatosis does not increase the promoter activity

Proteinase 3 is the major autoantigen in patients with Wegener's granulomatosis. Earlier studies have shown that circulating leucocytes from patients with Wegener's granulomatosis show elevated proteinase 3 surface expression and mRNA levels. Wegener's granulomatosis patients also have increased levels of proteinase 3 in plasma. A single nucleotide polymorphism (SNP) (-564 A/G SNP) in the promoter region has been associated with disease. This SNP introduces a new potential Sp1 transcription factor binding site that may be responsible for the observed up-regulated expression of proteinase 3. To investigate this a 740 base pair long region of the promoter was cloned from genomic DNA. The disease-associated -564 A/G, as well as a control -621 A/G exchange, were introduced by polymerase chain reaction mutagenesis and cloned into a luciferase reporter vector. Endogenous expression levels of proteinase 3 mRNA and promoter activity of the cloned constructs were measured in three myeloid cell lines, HL-60, U937 and NB-4, and in epithelial HeLa cells. The results demonstrate a good correlation between the endogenous proteinase 3 mRNA expression and the promoter activity, as judged by luciferase activity. However, no significant differences in activity between the wild-type, polymorphic and the mutated control variant were found. In conclusion, the -564 A/G polymorphism is not responsible for the increased expression levels seen in myeloid cells from patients with Wegener's granulomatosis.

New genomic region for Wegener's granulomatosis as revealed by an extended association screen with 202 apoptosis-related genes

Wegener's granulomatosis (WG) is a systemic disease with complex genetic background. It is characterized by necrotizing granulomatous inflammation of the upper and lower respiratory tract, glomerulonephritis, vasculitis and the presence of antineutrophil cytoplasmatic autoantibodies (C-ANCAs) in sera of patients. Here, we report on an extended association screen (EAS) with 202 microsatellite markers, representing apoptosis-related genes and further genes down-regulated in apoptotic neutrophils, using pooled DNA of 150 Northern German patients suffering from WG and 100 healthy Northern German controls. Six microsatellite allele patterns were found significantly associated with WG, three of which could be confirmed by individual genotyping. One marker remained significantly associated after multiple corrections. This marker representing the retinoid X receptor beta gene (RXRB, P=7.60x10(-6), distance to gene: approximately 5.3 kb) is localised in the major histocompatibility complex (MHC) region between the HLA-DPB1 and DAXX genes. HLA-DPB1 typing and fine mapping of the region with additional microsatellites and single-nucleotide polymorphisms (SNPs) revealed a strong association of WG with the significantly over-represented DPB1*0401 ( P=1.51x10(-10), OR=3.91) allele compared with the control cohort. In addition, an extended haplotype DPB1*0401/RXRB03 was identified showing an even stronger association with WG ( P=7.13x10(-17), OR=6.41). These results represent the strongest association of a genomic region with WG, suggesting a major genetic contribution in the aetiology of the disease. Thus, our data demonstrate that EAS may be a valuable alternative approach for determining genetic predisposition factors in multifactorial diseases.

Different gender-associated genotype risks of Wegener's granulomatosis and microscopic polyangiitis

Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA) are systemic small vessel vasculitides associated with ANCA (AAV). Predominant Th1 and Th2 cytokine patterns have been reported for WG and MPA, respectively. Consequently, genotypes suppressing Th1 responses or augmenting Th2 responses may be more frequent in MPA than in WG. Transforming growth beta1 (TGF-beta1) and interleukin-10 (IL-10) genes may modify the course of vasculitis. Therefore, we investigated associations between genotype frequencies of functional polymorphisms of these cytokine genes and clinical manifestations in AAV. One hundred sixty-one AAV patients and 153 healthy blood donors were genotyped for the biallelic polymorphism in codon 25 of the TGF-beta1 gene and the biallelic polymorphism at position -1082 of the IL-10 gene. No difference was found for TGF-beta1 codon 25 polymorphism between control and patient groups. In contrast, a significant shift toward the homozygous AA genotype of the IL-10 (-1082) polymorphism was found in WG (25%, p<0.005) and MPA patients (39%; p<0.00001) compared to controls (10.5%). Furthermore, in MPA the AA homozygous genotype was significantly more frequent in females (62.5%) compared to males (20%, p<0.05). A contribution of the TGF-beta1 codon 25 polymorphism to the susceptibility-defining genetic backgrounds of AAV appears unlikely. In contrast, our findings suggest a role of the enhanced IL-10 (-1082) PM in WG and MPA with a significant gender difference in MPA.

An analysis of CTLA-4 and proinflammatory cytokine genes in Wegener's granulomatosis

OBJECTIVE

The precipitating event(s) that triggers Wegener's granulomatosis (WG) is unknown. Cytokines, costimulatory molecules, and counterregulatory molecules control the quality and intensity of immune responses. Thus, they are relevant candidates for genetic studies of immune dysregulation in WG, the pathogenesis of which may be facilitated by multiple acquired and/or inherited factors. This study was undertaken to investigate possible genetic associations of various proinflammatory cytokines and CTLA-4, a receptor for T cell inhibition, with WG.

METHODS

Using polymerase chain reaction-based DNA genotyping, we investigated the polymorphisms located in the genes encoding a variety of proinflammatory cytokines and CTLA-4 in 117 American patients with WG and 123 ethnically matched healthy controls.

RESULTS

Compared with controls, patients with WG had a significantly lower frequency of homozygosity for the shortest allele (designated allele 86) of the Ctla4 microsatellite polymorphism (AT)n located in the 3'-untranslated region (3'-UTR) of exon 3 (47.0% versus 69.9%; P = 0.0005). Significant differences between patients and controls in the allelic and genotypic frequencies of polymorphisms in the other cytokine and cytokine receptor genes studied (tumor necrosis factor alpha [TNFalpha], TNF receptor I [TNFRI], TNFRII, interleukin-1beta [IL-1beta], IL-6) were not found.

CONCLUSION

The Ctla4 (AT)n 86 allele has been previously demonstrated to be crucial for maintenance of normal levels of CTLA-4 expression and balance between T cell activation and inhibition. Our results in American patients confirm findings from a Scandinavian cohort in which a positive association between WG and longer alleles of (AT)n in the Ctla4 3'-UTR was demonstrated. Diminished frequencies of the most effective allele for CTLA-4 expression may represent a WG-related susceptibility mutation that accounts, in part, for increased T cell activation and clonal expansion in WG. Blockade of T cell costimulation using CTLA-4Ig might be a useful therapeutic intervention, providing an alternative or complementary approach to conventional treatment with immunosuppressive agents.

FcγRIIIb Allele-Sensitive Release of α-Defensins: Anti-Neutrophil Cytoplasmic Antibody-Induced Release of Chemotaxins

Antineutrophil cytoplasmic Abs (ANCA) can activate neutrophils in an FcgammaR-dependent manner, but the link between this ANCA-induced effect and mononuclear cell activation with the characteristic granuloma formation of Wegener's granulomatosis is unclear. Human alpha-defensins, small cationic antimicrobial peptides, are found in neutrophils and have chemotactic activity for T cells, dendritic cells, and monocytes. In this study, we quantitated the release of alpha-defensins (human neutrophil peptides 1-3) from human neutrophils after targeted FcgammaR cross-linking (XL). Homotypic XL of FcgammaRIIa, FcgammaRIIIb, or heterotypic XL of both receptors resulted in significant release of alpha-defensins, an effect also induced by both human polyclonal and murine monoclonal cytoplasmic staining ANCA (anti-proteinase 3). This release of alpha-defensins, as well as of other granule constituents (ANCA targets anti-proteinase 3 and myeloperoxidase and elastase), was significantly greater in donors homozygous for the NA1 allele of FcgammaRIIIb than in donors homozygous for NA2. Interestingly, the ANCA-induced release was completely inhibited by the IgG Fc-binding peptide TG19320, which blocks the IgG-Fc region from binding to FcgammaR. Based on their chemotactic properties, alpha-defensins and their release by ANCA may contribute to modulation of the acquired immune response and to granuloma formation. The greater activity of the FcgammaRIIIB-NA1 genotype may also explain the greater severity of disease and its flare-ups in patients with this allele.

Differences in CCR5 expression on peripheral blood CD4+CD28- T-cells and in granulomatous lesions between localized and generalized Wegener's granulomatosis

Wegener's granulomatosis (WG) is an autoimmune disease characterized by granulomatous lesions and a necrotizing vasculitis. Th1-type-cells lacking CD28 are expanded independent of age and immunosuppressive therapy in WG. To address their migratory properties of CD4(+)CD28(-) T-cells we studied the expression of the inducible inflammatory Th1-type chemokine receptor CCR5 in localized WG and generalized WG. Expansion of CD4(+)CD28(-) T-cells was more prominent in generalized WG compared to localized WG. In localized WG a larger fraction of CD4(+)CD28(-) T-cells displayed CCR5 expression compared to generalized WG. CCR5 expression was also higher in granulomatous lesions in localized WG. Higher levels of CCR5 expression on CD4(+)CD28(-) T-cells in localized WG may favor stronger CCR5-mediated recruitment of this T-cell subset into granulomatous lesions in localized WG. Expansion of Th-1-type CD4(+)CD28(-)CCR5(+) effector memory T-cells might contribute to disease progression and autoreactivity, either directly, by maintaining the inflammatory response, or as a result of bystander activation.