Monocyte alterations in rheumatoid arthritis are dominated by preterm release from bone marrow and prominent triggering in the joint.

OBJECTIVE: Rheumatoid arthritis (RA) accompanies infiltration and activation of monocytes in inflamed joints. We investigated dominant alterations of RA monocytes in bone marrow (BM), blood and inflamed joints. METHODS: CD14+ cells from BM and peripheral blood (PB) of patients with RA and osteoarthritis (OA) were profiled with GeneChip microarrays. Detailed functional analysis was performed with reference transcriptomes of BM precursors, monocyte blood subsets, monocyte activation and mobilisation. Cytometric profiling determined monocyte subsets of CD14++CD16-, CD14++CD16+ and CD14+CD16+ cells in BM, PB and synovial fluid (SF) and ELISAs quantified the release of activation markers into SF and serum. RESULTS: Investigation of genes differentially expressed between RA and OA monocytes with reference transcriptomes revealed gene patterns of early myeloid precursors in RA-BM and late myeloid precursors along with reduced terminal differentiation to CD14+CD16+monocytes in RA-PB. Patterns associated with tumor necrosis factor/lipopolysaccharide (TNF/LPS) stimulation were weak and more pronounced in RA-PB than RA-BM. Cytometric phenotyping of cells in BM, blood and SF disclosed differences related to monocyte subsets and confirmed the reduced frequency of terminally differentiated CD14+CD16+monocytes in RA-PB. Monocyte activation in SF was characterised by the predominance of CD14++CD16++CD163+HLA-DR+ cells and elevated concentrations of sCD14, sCD163 and S100P. CONCLUSION: Patterns of less mature and less differentiated RA-BM and RA-PB monocytes suggest increased turnover with accelerated monocytopoiesis, BM egress and migration into inflamed joints. Predominant activation in the joint indicates the action of local and primary stimuli, which may also promote adaptive immune triggering through monocytes, potentially leading to new diagnostic and therapeutic strategies.

Type I interferon as a biomarker in autoimmunity and viral infection: a leukocyte subset-specific analysis unveils hidden diagnostic options.

Interferon alpha and its surrogates, including IP-10 and SIGLEC1, paralleled changes of disease activity in systemic lupus erythematosus (SLE). However, the whole blood interferon signature (WBIFNS)-the current standard for type I IFN assessment in SLE-does not correlate with SLE disease activity in individual patients over time. The underlying causes for this apparent contradiction have not been convincingly demonstrated. Using a multicenter dataset of gene expression data from leukocyte subsets in SLE, we identify distinctive subset-specific contributions to the WBIFNS. In a subsequent analysis, the effects of type I interferon on cellular blood composition in patients with SLE and hepatitis B were also studied over time. We found that type I interferon mediates significant alterations in whole blood composition, including a neutropenia and relative lymphocytosis. Given different effects of type 1 interferon on different leukocyte subsets, these shifts confound measurement of a type 1 interferon signature in whole blood. To minimize and overcome these limitations of the WBIFNS, we suggest to measure IFN-induced transcripts or proteins in a specific leukocyte subset to improve clinical impact of interferon biomarkers. KEY MESSAGES: Myeloid cells contribute more to the WBIFNS in SLE than their lymphocytic counterpart. Very similar leukocyte subsets reveal distinctive IFN signatures. IFN alpha mixes up composition of blood and leads to a preferential neutropenia, yielding relative lymphocytosis.

Complete Remission in Systemic Skin Interdigitating Dendritic Cell Sarcoma after ABVD Chemotherapy.

Interdigitating dendritic cell sarcoma (IDCS) is a rare and aggressive neoplasm that is thought to arise from dendritic cells. This disease usually involves the lymph nodes and, rarely, extra-nodal sites. We report a 62-year-old man presenting skin nodules in the head, body, and extremities, as well as bone marrow involvement. Morphologic analysis of a biopsied specimen from the skin lesion was consistent with IDCS. Immunohistochemical staining demonstrated that the tumor cells were positive for IDCS-associated antigens such as CD4, CD45, CD68 (KP-1), and S-100 protein. Complete remission was achieved by treatment with 6 cycles of ABVD (adriamycin, bleomycin, vinblastine, and dacarbazine) chemotherapy. Although the optimal treatment of IDSC remains unknown, the experience in the current case supports the notion that ABVD chemotherapy may be effective for IDCS, and further extends this idea to rare patients presenting multiple skin lesions.

Cell-specific type I IFN signatures in autoimmunity and viral infection: what makes the difference?

Gene expression profiling of peripheral blood mononuclear cells (PBMCs) has revealed a crucial role for type I interferon (IFN) in the pathogenesis of systemic lupus erythematosus (SLE). However, it is unclear how particular leucocyte subsets contribute to the overall type I IFN signature of PBMCs and whole blood samples.Furthermore, a detailed analysis describing the differences in the IFN signature in autoimmune diseases from that observed after viral infection has not been performed to date. Therefore, in this study, the transcriptional responses in peripheral T helper cells (CD4(+)) and monocyte subsets (CD16(-) inflammatory and CD16(+) resident monocytes) isolated from patients with SLE, healthy donors (ND) immunised with the yellow fever vaccine YFV-17Dand untreated controls were compared by global gene expression profiling.It was striking that all of the transcripts that were regulated in response to viral exposure were also found to be differentially regulated in SLE, albeit with markedly lower fold-change values. In addition to this common IFN signature, a pathogenic IFN-associated gene signature was detected in the CD4(+) T cells and monocytes from the lupus patients. IL-10, IL-9 and IL-15-mediated JAK/STAT signalling was shown to be involved in the pathological amplification of IFN responses observed in SLE. Type I IFN signatures identified were successfully applied for the monitoring of interferon responses in PBMCs of an independent cohort of SLE patients and virus-infected individuals. Moreover, these cell-type specific gene signatures allowed a correct classification of PBMCs independent from their heterogenic cellular composition. In conclusion, our data show for the first time that monocytes and CD4 cells are sensitive biosensors to monitor type I interferon response signatures in autoimmunity and viral infection and how these transriptional responses are modulated in a cell- and disease-specific manner.

Cumulative association of eight susceptibility genes with systemic lupus erythematosus in a Japanese female population.

Although large-scale studies established many susceptibility genes to systemic lupus erythematosus (SLE), effect of each gene is not sufficiently large to be used alone to identify individuals with strong genetic predisposition. In this study, we analyzed the cumulative number of risk alleles at eight established susceptibility loci, HLA-DRB1, IRF5, STAT4, BLK, TNFAIP3, TNIP1, FCGR2B and TNFSF13, in 282 Japanese female SLE and 222 healthy female controls. The average number of risk alleles was significantly increased in SLE (8.07±1.60) than healthy controls (7.02±1.64) (P=1.63 × 10(-12)). Significant gene-gene interaction was not detected. When the subjects carrying seven risk alleles were used as a reference, the odds ratio (OR) for individuals carrying 10 and 11-13 risk alleles were 4.17 (95% confidence interval (CI) 1.89-9.19, P=0.0002) and 8.77 (95% CI 1.92-40.0, P=0.0016), respectively. In contrast, subjects with ≤4 risk alleles were significantly decreased in SLE (OR 0.15, CI 0.03-0.67, P=0.007). The proportion of the patients with neurologic disorder was significantly increased in those carrying ≥10 risk alleles than those with <10 (OR 2.30, CI 1.09-4.83, P=0.025). This study suggested that the cumulative number of risk alleles may efficiently distinguish groups with high and low genetic predisposition to SLE and its severe manifestation.

Exon 6 variants carried on systemic lupus erythematosus (SLE) risk haplotypes modulate IRF5 function.

Interferon regulatory factor 5 (IRF5) regulates innate immune responses to viral infection. IRF5 genetic variants have been shown to be strongly associated with risk for systemic lupus erythematosus (SLE). Functional roles of IRF5 exon 6 structural variants that occur as part of a SLE risk-associated haplotype, including a 30-bp in/del (in/del-10) and a 48-bp splice-site variant (SV-16), have not been established. In this study, we used IRF5-deficient cells overexpressing human IRF5 (hIRF5) variants to investigate the roles of exon 6 in/del-10 and SV-16 in regulation of the apoptosis response, nuclear translocation, and ability to transactivate IRF5 responsive cytokines. We found that expression of IRF5 isoforms including either SV-16 or in/del-10 confers ability of IRF5 to impair the apoptotic response and correlates with reduced capacity for IRF5 nuclear translocation in MEFs after a DNA-damaging stimulus treatment. Interestingly, the presence or absence of both SV-16 and in/del-10 results in abrogation of both the anti-apoptotic and enhanced nuclear translocation effects of IRF5 expression. Only cells expressing IRF5 bearing SV-16 show increased IL-6 production upon lipopolysaccharide stimulation. MEFs expressing hIRF5 variants containing in/del-10 showed no significant difference from the control; however, cells carrying hIRF5 lacking both SV-16 and in/del-10 showed reduced IL-6 production. Our overall findings suggest that exon 6 SV-16 is more potent than in/del-10 for IRF5-driven resistance to apoptosis and promotion of cytokine production; however, in/del-10 co-expression can neutralize these effects of SV-16.

Association of calcineurin A gamma subunit (PPP3CC) and early growth response 3 (EGR3) gene polymorphisms with susceptibility to schizophrenia in a Japanese population.

To examine the association of PPP3CC (rs10108011 and rs2461491) and EGR3 (rs3750192) single-nucleotide polymorphisms (SNPs) with Japanese schizophrenia, we performed a case-control association study using 337 patients and 369 healthy controls. As a result, by our moderated cohort-size study, PPP3CC and EGR3 are not genetic risk factors for schizophrenia, whereas meta-analysis showed weak association of rs10108011 with schizophrenia in the Japanese population (odds ratio (OR)=1.12, P=0.01).

Lack of association between tyrosine kinase 2 (TYK2) gene polymorphisms and susceptibility to SLE in a Japanese population.

Tyrosine kinase 2 (TYK2) is a type I interferon (IFN) signaling pathway gene and was previously reported to be a risk factor for systemic lupus erythematosus (SLE) in Caucasian populations. In order to test for its genetic association with SLE in a Japanese population, TYK2 single nucleotide polymorphisms (SNPs), rs2304256, rs12720270 and rs280519, were genotyped. A case-control association study was performed in a total of 411 Japanese SLE patients and 467 healthy controls. Linkage disequilibrium (LD) among TYK2 SNPs was examined. According to the data from 94 healthy controls, non-synonymous rs2304256 resulting in Val --> Phe substitution was revealed to be in a LD with rs12720270 and rs280519. Therefore, we further genotyped rs2304256 as a tag SNP in the full sample sets. As a result, no differences in genotype distribution and allelic frequencies of rs2304256 were found between SLE patients and healthy controls. In conclusion, TYK2 is not a genetic risk factor for SLE in a Japanese population. Our result suggests that there is an ethnic difference in the susceptibility genes for SLE.

Association of IRF5 polymorphisms with systemic lupus erythematosus in a Japanese population: support for a crucial role of intron 1 polymorphisms.

OBJECTIVE: To determine whether the IRF5 gene, which encodes interferon regulatory factor 5, is associated with systemic lupus erythematosus (SLE) in a Japanese population. METHODS: A case-control study was performed in 277 SLE patients and 201 healthy controls. Associations between the IRF5 genotype and levels of messenger RNA (mRNA) for interferon (IFN) pathway genes were examined using an mRNA expression database of HapMap samples. RESULTS: Carriers of the rs2004640T single-nucleotide polymorphism (SNP) were slightly increased among SLE patients (58.8%) as compared with controls (50.2%). When data from our Japanese population were combined with previously published data from a Korean population, the T allele frequency was found to be significantly increased in SLE patients (P = 8.3 x 10(-5)). While no association was observed for the rs10954213 SNP or the exon 6 insertion/deletion, significant associations with 3 intron 1 SNPs (-4001, rs6953165, and rs41298401) were found. The allele frequency of rs41298401G was significantly decreased in SLE patients (13.0% versus 18.7% in controls; P = 0.017), and the allele frequency of rs6953165G, which was in absolute linkage disequilibrium with -4001A, was increased in SLE patients (8.8% versus 5.2% in controls; P = 0.034). The Caucasian risk haplotype was not present; instead, a protective haplotype carrying rs2004640G, rs41298401G, the deletion in exon 6, and rs10954213A was identified. SNP rs10954213, but not intron 1 SNPs, was associated with IRF5 at the mRNA level; nevertheless, intron 1 SNPs were also associated with levels of mRNA for several IFN pathway genes, suggesting a functional role. CONCLUSION: IRF5 was found to be associated with SLE in Asian populations. Intron 1 SNPs, rather than exon 6 and 3'-untranslated region polymorphisms, appeared to play a crucial role.

Three functional variants of IFN regulatory factor 5 (IRF5) define risk and protective haplotypes for human lupus.

Systematic genome-wide studies to map genomic regions associated with human diseases are becoming more practical. Increasingly, efforts will be focused on the identification of the specific functional variants responsible for the disease. The challenges of identifying causal variants include the need for complete ascertainment of genetic variants and the need to consider the possibility of multiple causal alleles. We recently reported that risk of systemic lupus erythematosus (SLE) is strongly associated with a common SNP in IFN regulatory factor 5 (IRF5), and that this variant altered spicing in a way that might provide a functional explanation for the reproducible association to SLE risk. Here, by resequencing and genotyping in patients with SLE, we find evidence for three functional alleles of IRF5: the previously described exon 1B splice site variant, a 30-bp in-frame insertion/deletion variant of exon 6 that alters a proline-, glutamic acid-, serine- and threonine-rich domain region, and a variant in a conserved polyA+ signal sequence that alters the length of the 3' UTR and stability of IRF5 mRNAs. Haplotypes of these three variants define at least three distinct levels of risk to SLE. Understanding how combinations of variants influence IRF5 function may offer etiological and therapeutic insights in SLE; more generally, IRF5 and SLE illustrates how multiple common variants of the same gene can together influence risk of common disease.

Specific combinations of HLA-DR2 and DR3 class II haplotypes contribute graded risk for disease susceptibility and autoantibodies in human SLE.

The human leukocyte antigen (HLA) Class II antigen presentation alleles DR and DQ are associated with susceptibility to systemic lupus erythematosus (SLE) and the production of lupus-related autoantibodies. Here, we explore the effect of different combinations of Class II risk haplotypes in a large, multi-center collection of 780 SLE families. Haplotypes bearing the DRB1*1501/DQB1*0602 (DR2) and DRB1*0301/DQB1*0201 (DR3) alleles were present in nearly two-thirds of SLE cases and were significantly associated with disease susceptibility in both family-based and case-control study designs. DR3-containing haplotypes conferred higher risk for disease than DR2, and individual homozygous for DR3 or compound heterozygous for DR3 and DR2 showed the highest risk profile. DR2 haplotypes were also found to be associated with antibodies to the nuclear antigen Sm, and, as previously observed, DR3 genotypes were associated with Ro and La autoantibodies. Interestingly, SLE cases and unaffected family members who were DR2/DR3 compound heterozygotes showed particularly strong risk of developing antibodies to Ro, and were enriched for La and Sm. These data provide convincing evidence that particular combinations of HLA Class II DR2 and DR3 haplotypes are key determinants of autoantibody production and disease susceptibility in human SLE.

Diversity of human immune system multigene families and its implication in the genetic background of rheumatic diseases.

A large number of molecules in the immune system are encoded by multigene families. These genes are rich in pairs of activating and inhibitory receptors that share the same ligands, thereby playing a crucial role in immunoregulation. Furthermore, multigene families tend to be highly polymorphic. Thus, multigene families are strong candidates for containing genes that enhance susceptibility to immune system-related diseases. Here, we review studies from our group, as well as other investigators, on three multigene families that belong to the immunoglobulin (Ig) - like receptor superfamily: Fcgamma receptor (FCGR), killer cell Ig-like receptor (KIR) and leukocyte Ig-like receptor (LILR) families. FCGR genes have been implicated in susceptibility to systemic lupus erythematosus (SLE). In FCGR2B encoding an inhibitory receptor expressed in B cells, monocytes and dendritic cells, a polymorphism within the transmembrane region, Ile232Thr, was identified and found to be associated with susceptibility to SLE in three Asian populations. Functional analyses revealed that SLE-associated FcgammaRIIb-232Thr was less efficient in entering the membrane lipid raft, and exhibited reduced inhibitory potential against B cell receptor signaling. Although the frequency of this polymorphism was low in Caucasians, another polymorphism within the promoter region was reported to be associated with SLE. KIR/HLA combinations have been shown to be associated with various autoimmune and infectious diseases. Recently, LILR families have also been found to be highly polymorphic, and association with several diseases has been identified. These results emphasize the role of multigene families in the diversity of human immune response and susceptibility to diseases.

Role of Fc gamma receptor IIb polymorphism in the genetic background of systemic lupus erythematosus: insights from Asia.

FCGR2B codes for an inhibitory receptor expressed in B cells and monocytes. Polymorphisms of Fcgr2b in mice have been shown to be associated with autoimmune diseases including systemic lupus erythematosus (SLE) and targeted disruption of Fcgr2b renders mice susceptible to induced or spontaneous autoimmunity, depending on the genetic background. Polymorphism screening of FCGR2B has been hampered by the complexity and extreme homology among FCGR family members. We established a specific genotyping system, detected a SNP that changes position 232 amino acid in the transmembrane region from Ile to Thr and found a significant association of 232Thr with SLE in the Japanese, Thai and Chinese populations. In contrast, promoter polymorphism of FCGR2B, but not Ile232Thr, was shown to be associated with SLE in Caucasians. Linkage disequilibrium was observed among FCGR2A, 2B, 3A and 3B genes with varying degrees, but in the Asian populations, each of FCGR2B, 3A and 3B genes was suggested to contribute to the susceptibility to SLE. These results indicate that FCGR2B is a susceptibility gene to SLE in the context of a genetic background, both in humans and mice.

FcgammaRIIB Ile232Thr transmembrane polymorphism associated with human systemic lupus erythematosus decreases affinity to lipid rafts and attenuates inhibitory effects on B cell receptor signaling.

The B cell inhibitory receptor FcgammaRIIB plays crucial roles in the maintenance of self-tolerance. We have identified a polymorphism FCGR2B c.695T>C that results in the non-conservative replacement of 232Ile at the transmembrane helix to Thr and demonstrated the association of the polymorphism with susceptibility to systemic lupus erythematosus (SLE) in Asians. In this study, we examined the impact of FCGR2B c.695T>C on the functional properties of FcgammaRIIB by expressing each allele product in a human B cell line ST486 lacking endogenous FcgammaRIIB. FcgammaRIIB 232Thr was found to be significantly less potent than wild-type 232Ile in inhibiting B cell receptor (BCR)-mediated phosphatidylinositol-3,4,5-trisphosphate accumulation, Akt and PLCgamma2 activation and calcium mobilization, and to display decreased levels of tyrosine phosphorylation and SH2-containing 5'-inositolphosphate phosphatase recruitment compared with 232Ile after IgG Fc-mediated coligation with BCR. Notably, a quantitative analysis of the subcellular distribution of FcgammaRIIB using 125I-labeled anti-FcgammaRIIB revealed that FcgammaRIIB 232Thr is less effectively distributed to detergent-insoluble lipid rafts than 232Ile, findings in accordance with the importance of the transmembrane amino acid residues, in particular large hydrophobic amino acids including Ile, in the association of membrane proteins with lipid rafts. Given the crucial roles of lipid rafts in integrating BCR signaling, decreased association of FcgammaRIIB 232Thr could contribute to its impaired inhibitory potential. Collectively, the present findings indicate that the Ile232Thr substitution affects the localization and function of FcgammaRIIB and that the molecular mechanism may link the polymorphism and susceptibility to SLE.

Progress towards understanding the genetic pathogenesis of systemic lupus erythematosus.

In order to better understand the genetic factors that initiate systemic lupus erythematosus (SLE), we are using both linkage and association approaches to identify susceptibility genes for the disease. Association studies have recently identified three HLA Class II haplotypes as well as a functional missense polymorphism in protein tyrosine phosphatase (PTP) PTPN22 as important risk alleles for SLE. Here, we will review these data, and explain how these findings contribute to an understanding of the genetic architecture of human SLE.

CD72 polymorphisms associated with alternative splicing modify susceptibility to human systemic lupus erythematosus through epistatic interaction with FCGR2B.

We previously reported association of FCGR2B-Ile232Thr with systemic lupus erythematosus (SLE) in three Asian populations. Because polymorphism of CD72, another inhibitory receptor of B cells, was associated with murine SLE, we identified human CD72 polymorphisms, tested their association with SLE and examined genetic interaction with FCGR2B in the Japanese (160 SLE, 277 controls), Thais (87 SLE, 187 controls) and Caucasians (94 families containing SLE members). Four polymorphisms and six rare variations were detected. The former constituted two major haplotypes that contained one or two repeats of 13 nucleotides in intron 8 (designated as *1 and *2, respectively). Although association with susceptibility to SLE was not detected, the *1 allele was significantly associated with nephritis among the Japanese patients (P=0.024). RT-PCR identified a novel alternatively spliced (AS) transcript that was expressed at the protein level in COS-7 transfectants. The ratio of AS/common isoforms was strikingly increased in individuals with *2/*2 genotype when compared with *1/*1 (P=0.000038) or *1/*2 (P=0.0085) genotypes. Using the two Asian cohorts, significant association of FCGR2B-232Thr/Thr with SLE was observed only in the presence of CD72-*1/*1 genotype (OR 4.63, 95% CI 1.47-14.6, P=0.009 versus FCGR2B-232Ile/Ile plus CD72-*2/*2). Minigene assays demonstrated that the 13-nucleotide repeat and 4 bp deletion within the same haplotype of intron 8 could regulate alternative splicing. The AS isoform lacks exon 8, and is deduced to contain 49 amino acid changes in the membrane-distal portion of the extracellular domain, where considerable amino acid changes are known in CD72(c) allele associated with murine SLE. These results indicated that the presence of CD72-*2 allele decreases risk for human SLE conferred by FCGR2B-232Thr, possibly by increasing the AS isoform of CD72.

Genetic association of the R620W polymorphism of protein tyrosine phosphatase PTPN22 with human SLE.

We genotyped 525 independent North American white individuals with systemic lupus erythematosus (SLE) for the PTPN22 R620W polymorphism and compared the results with data generated from 1,961 white control individuals. The R620W SNP was associated with SLE (genotypic P=.00009), with estimated minor (T) allele frequencies of 12.67% in SLE cases and 8.64% in controls. A single copy of the T allele (W620) increases risk of SLE (odds ratio [OR]=1.37; 95% confidence interval [CI] 1.07-1.75), and two copies of the allele more than double this risk (OR=4.37; 95% CI 1.98-9.65). Together with recent evidence showing association of this SNP with type 1 diabetes and rheumatoid arthritis, these data provide compelling evidence that PTPN22 plays a fundamental role in regulating the immune system and the development of autoimmunity.

Genetic background of Japanese patients with antineutrophil cytoplasmic antibody-associated vasculitis: association of HLA-DRB1*0901 with microscopic polyangiitis.

OBJECTIVE: To examine association of 8 candidate genes with susceptibility to antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in Japanese patients. Little is known on the genetic background of AAV in Japanese patients mainly because of the difficulty in collecting a sufficient number of samples for the genetics study. METHODS: Sixty-nine patients, including 50 with microscopic polyangiitis (MPA), were recruited in a multicenter study. Among them, 64 patients were positive for myeloperoxidase (MPO)-ANCA. Associations of HLA-DRB1, tumor necrosis factor-alpha promoter (TNF), TNF receptor 2 (TNFR2), Fcgamma receptor IIa (FCGR2A), IIb (FCGR2B), IIIa (FCGR3A), IIIb (FCGR3B), and CTLA-4 (CTLA4) polymorphisms were examined in a case-control analysis. RESULTS: A significant association of HLA-DRB1*0901 with MPA (p = 0.0037, OR 2.44, 95% CI 1.33-4.46), as well as with MPO-ANCA positivity (p = 0.0014, OR 2.44, 95% CI 1.41-4.22), was detected. There was no difference in the TNF promoter haplotype frequencies between patients with MPA and controls, excluding the possibility that the association of DRB1*0901 was secondarily caused by linkage disequilibrium with TNF. No association was observed for TNFR2, FCGR, or CTLA4 with MPA, nor with the presence of MPO-ANCA, although the combined genotype FCGR2A-131H/H and 3A-176F/F was increased in patients with MPA (p = 0.025). CONCLUSION: There was an association of HLA-DRB1*0901 with MPA and MPO-ANCA positive vasculitis in Japanese patients.