An association between susceptibility to rheumatoid arthritis and the Fc receptor‐like 3 gene (FCRL3) has been reported in a Japanese population. A case–control study showed that the strongest evidence of the association was derived from a polymorphism in the promoter region of FCRL3, which has a regulatory effect on the expression of the gene.
To validate the findings of this previous report by examining the −169C→T single nucleotide polymorphism (SNP) in a large cohort.
752 unrelated cases and 940 controls were genotyped. All the samples were from the same ethnic background as the original study. Genotyping was done using 5′ allelic discrimination assays. Association between susceptibility to rheumatoid arthritis and −169C→T SNP was examined by χ2 testing.
As in the previous study, the SNP showed significant differences between cases and controls (p = 0.022, odds ratio = 1.18, 95% confidence interval 1.02 to 1.35).
This result supports a genetic association of the FCRL3 promoter polymorphism with rheumatoid arthritis.
; rheumatoid factor; replication
Association of a functional promoter polymorphism mapping to the Fc receptor-like 3 (FCRL3) gene has recently been reported and replicated with rheumatoid arthritis (RA) in Japanese populations. The aim of this study was to investigate association of the FCRL3 gene with RA in UK subjects. DNA was available from 1065 patients with RA and 2073 population controls from the UK. Four single nucleotide polymorphism (SNP) markers (FCRL3-169*C/T (fclr3_3, rs7528684), fclr3_4 (rs11264799), fclr3_5 (rs945635), fclr3_6 (rs3761959)) all previously associated with RA in a Japanese population were genotyped in 761 RA samples and 484 controls. In the remaining samples, only the putative disease causal polymorphism, FCRL3-169*C/T, was tested. Genotyping was performed using either the Sequenom MassArray iPlex platform or a 5' Allelic discrimination assay (Taqman, ABI). Extensive linkage disequilibrium was present across the promoter SNPs genotyped (r2 values = 0.60-0.98). Allele frequencies did not differ between RA cases and controls either for the putative disease causal polymorphism (odds ratio FCRL3-169*C allele = 0.97 (0.87-1.07), p = 0.51) or for the other SNPs tested. Similarly, no association was detected with RA using haplotype analysis or when stratification by shared epitope carriage or by presence of rheumatoid factor was undertaken. This study was powered to detect an effect size of 1.24 or greater for the FCRL3-169*C/T functional promoter polymorphism but no evidence for association was detected, suggesting that this gene will not have a substantial effect in determining susceptibility to RA in populations of Northern European descent.
CD4+FoxP3+ regulatory T cells (Treg) suppress effector T cells and prevent autoimmune disease. Treg function is deficient in active rheumatoid arthritis (RA), a loss which may play a role in the pathogenesis of this disease. We previously showed that a single nucleotide polymorphism in the Fc Receptor Like-3 (FCRL3) gene led to higher expression of FcRL3 on Treg+ and that FcRL3 Treg are functionally deficient in comparison to FcRL3− Treg. The objective of this work was to investigate the potential role of FcRL3 in rheumatoid arthritis.
A cross-sectional study was performed to evaluate the FCRL3 -169 genotype and FcRL3 expression on T cell subsets, including Treg, from peripheral blood samples of 51 patients with RA enrolled in the UCSF RA Cohort. Clinical data were obtained from the UCSF RA Cohort database.
We found that patients with the FCRL3 -169C allele (genotype C/C or C/T) expressed significantly higher levels of FcRL3 on Treg, and on CD8+ and TCRγδ+ T cells, in comparison to RA patients with the T/T genotype. Higher FcRL3 expression on these T cell subpopulations correlated with RA disease activity in those patients harboring the FCRL3 -169C allele. Furthermore, FcRL3 expression on Treg was higher in patients with erosive RA disease and the FCRL3 -169C allele was overrepresented in patients with erosive RA disease.
FcRL3 expression, which is strongly associated with the presence of the FCRL3 -169C allele, may serve as a biomarker of RA disease activity.
The Fc receptor like 3 (FCRL3) molecule, involved in controlling B cell signalling, may contribute to the autoimmune disease process. Recently a genome wide screen detected association of neighbouring gene FCRL5 with Graves’ disease (GD). To determine whether FCRL5 represents a further independent B cell signaling GD susceptibility loci we screened 12 tag SNPs, capturing all known common variation within FCRL5, in 5192 UK Caucasian GD index cases and controls.
A case control association study investigating twelve tag SNPs within FCRL5 which captured the majority of known common variation within this gene region.
A dataset comprising 2504 UK Caucasian GD patients and 2688 geographically matched controls taken from the 1958 British Birth cohort.
We used the chi-squared test and haplotype analysis to investigate association between the tag SNPs and GD before performing regression analysis to determine if association at FCRL5 was independent of the known FCRL3 association.
Three of the FCRL5 tag SNPs, rs6667109, rs3811035 and rs6692977 showed association with GD (P=0.015-0.001, OR=1.15-1.16). Logistic regression performed on all FCRL5 and, previously screened, FCRL3 tag SNPs revealed that association with FCRL5 was secondary to linkage disequilibrium with the FCRL3, rs11264798 and rs10489678 SNPs.
FCRL5 does not appear to be exerting an independent effect on the development of GD in the UK. Fine mapping of the entire FCRL region is required to determine the exact location of the etiological variant/s present.
Linkage disequilibrium; FCRL3; FCRL5; Graves’ disease; genome wide screening
Morphologically and functionally distinct subpopulations of human memory B (BMem) cells are identifiable by either their expression of CD27 or Fc receptor–like 4 (FCRL4), an immunoglobulin domain containing a receptor with strong inhibitory potential. We have conducted comparative transcriptome and proteome analyses of FCRL4+ and FCRL4− BMem cells and found that these two subsets have very distinctive expression profiles for genes encoding transcription factors, cell-surface proteins, intracellular signaling molecules, and modifiers of the cell-cycle status. Among the differentially expressed transcription factors, runt-related transcription factor 1 (RUNX1) transcript levels were up-regulated in FCRL4− cells, whereas RUNX2 transcripts were preferentially detected in FCRL4+ cells. In vitro evidence for FCRL4 promoter responsiveness and in vivo promoter occupancy suggested that RUNX transcription factors are involved in the generation of these BMem cell subpopulations. A distinctive signature profile was defined for the FCRL4+ BMem cells by their expression of CD11c, receptor activator for nuclear factor κB ligand, and FAS cell-surface proteins, in combination with increased levels of SOX5, RUNX2, DLL1, and AICDA expression. We conclude that this recently identified subpopulation of BMem cells, which normally resides in epithelial tissue-based niches, may serve a unique role in mucosal defense and, conversely, as a target for neoplastic transformation events.
Recently, the FCRL3 −169T>C (rs7528684) single-nucleotide polymorphism (SNP) has been demonstrated to be a risk factor of endometriosis related infertility. We studied whether the FCRL −169T>C SNP can be associated with endometriosis-related infertility in a sample of the Polish population
Using PCR–RFLP analysis we genotyped 141 infertile women with endometriosis and 519 fertile women. FCRL3 transcript levels were determined by reverse transcription and real-time quantitative PCR analysis in CD19+ B cells from women with endometriosis-associated infertility and fertile women
We found a significantly increased frequency of the FCRL3 C/C genotype in women with endometriosis-associated infertility than controls [OR = 1.681 (95 % CI = 1.120–2.522, p = 0.0116, pcorr = 0.0348)]. There was also a statistically increased frequency of the C/C and C/T genotypes in patients compared with controls [OR = 2.009 (95 % CI = 1.214–3.324, p = 0.0059, pcorr = 0.0177)]. The p value of the χ2 test for the trend observed for the FCRL3 −169T>C polymorphism was also statistically significant (ptrend = 0.0012, pcorr = 0.0036). We also found significantly increased FCRL3 transcript levels in carriers of the FCRL3 −169 CC vs TT and CT vs TT genotype both in women with endometriosis-related infertility (p = 0.012; p = 0.015) and fertile women (p = 0.017; p = 0.032)
FCRL3 −169T>C polymorphism alters the expression of FCRL3 and can be a risk factor of endometriosis-related infertility.
Polymorphisms; Endometriosis; Infertility
Fc receptor-like 3 (FCRL3) is a cell surface protein homologous to Fc receptors. The FCRL3 gene is present in humans but not in mice. We found that FCRL3 protein is expressed on 40% of human naturally occurring CD4+ regulatory T (nTreg) cells (CD4+CD25+CD127low). Sorted nTreg cells with the surface phenotype FCRL3+ and FCRL3− were both hypoproliferative to T cell receptor stimulation and both suppressive on proliferation of conventional T cells (CD4+CD25−) in vitro. They both expressed forkhead box p3 (Foxp3) protein, the intracellular regulatory T cell marker. However, in contrast to FCRL3− nTreg cells, FCRL3+ nTreg cells were not stimulated to proliferate by the addition of exogenous IL-2. In addition, Foxp3+ cells induced from conventional T cells by TGF-β treatment did not exhibit FCRL3 expression. These results suggest that the FCRL3+ subset of human nTreg cells identified in this study arise in vivo, and Foxp3 expression alone is not sufficient to induce FCRL3 expression. FCRL3 may be involved in human specific mechanisms to control the generation of nTreg cells.
Human; T Cells; Autoimmunity; Cell Surface Molecules; Cell Differentiation
Human leucocyte antigen is the only genetic risk factor for rheumatoid arthritis (RA) that has been consistently observed in different populations. A number of other genes such as PTPN22 and PADI4 showed population‐specific association with RA susceptibility. Recently, Fc receptor‐like 3 (FCRL3) gene was found to be associated with RA susceptibility in Japanese, but with conflicting results in other populations.
To investigate the association of FCRL3 polymorphism with RA susceptibility and severity in Dutch Caucasian patients with RA, as well as to perform a meta‐analysis to reveal the contribution of this gene to RA susceptibility.
A total of 931 Dutch RA cases and 570 unrelated Dutch controls were genotyped for four FCRL3 single‐nucleotide polymorphisms (SNPs). Genotyping was performed using the MassArray matrix‐assisted laser desorption ionisation‐time‐of‐flight mass spectrometry. Association of the FCRL3 SNPs with susceptibility to RA was examined by single‐marker, carrier and haplotype analysis.
Carrier analysis of the SNP (rs7528684) revealed the association of CC genotype with a higher risk of developing RA as compared with TT and TC carriers (p = 0.039 and OR = 1.31). There was no significant difference in the genotype and allele frequencies of all investigated SNPs between cases and controls. Meta‐analysis of all studies comparing 9467 individuals showed that the OR for the CC genotype to develop RA was 1.2 and the p value <0.001.
A promoter polymorphism of FCRL3 (rs7528684) is associated with an increased risk of developing RA in Dutch Caucasians, suggesting that this association is relevant for RA in both Japanese and Caucasian populations.
Fc Receptor-Like proteins are a family of cellular receptors homologous
to FcγRI, and predominantly expressed by B cells. They function to
co-stimulate or inhibit B cell receptor signaling through consensus ITAMs and
ITIMs, however the extracellular ligands of these receptors remain unknown or
controversial. In this study, we tested the ability of human FcRL proteins to
bind immunoglobulins and found FcRL4 and FcRL5 to be bona fide
Fc receptors. In cellular binding assays, FcRL4 bound efficiently to IgA and
FcRL5 binds all IgG isotypes with varied efficiency. In addition, we generated
monoclonal antibodies capable of specifically blocking these interactions. Given
their expression on activated B cells and potential for inhibitory signaling,
FcRL4 and FcRL5 are likely to be important for immune complex-dependent human B
cell regulation, and represent novel therapeutic targets for receptor blockade
Studies have shown a strong association of human leukocyte antigens-B51 (HLA-B51) with Behçet’s disease (BD). However, little is known about the association of non-HLA genes with BD. The polymorphisms of the Fc receptor-like 3 gene (FCRL3), −169C/T, −110A/G, +358C/G, and +1381A/G, have been reported to be associated with several autoimmune diseases. This study was designed to determine whether the polymorphisms of FCRL3 were associated with susceptibility to BD in a Chinese population mainly with ocular involvement.
A case-control study was performed in 245 Chinese BD patients and 289 controls. Four single nucleotide polymorphisms (SNPs; −169C/T, −110A/G, +358C/G, and +1381A/G) in FCRL3 were detected using polymerase chain reaction restriction fragment length polymorphisms (PCR-RFLP). HLA-B51 genotyping was performed by the PCR sequence specific primers method as described previously.
The results showed a significantly higher frequency of the G allele at the −110 site in BD patients compared with that in controls (corrected p=0.044, 75.3% versus 67.5%, χ2=7.72). Haplotype CGCG frequency was significantly higher in patients than in controls (corrected p=0.0096) whereas haplotype TACG frequency was significantly lower in patients compared with controls (corrected p=0.032). There was no relationship between clinical signs and FCRL3 polymorphisms. No significant difference was observed between patients and controls after HLA-B51 stratification concerning the four SNPs.
Our study suggests that the −110 G allele and the haplotype CGCG of FCRL3 are positively associated with BD in a Chinese population and that the haplotype ATCG might be a protective haplotype for BD.
The polymorphisms of the Fc receptor-like 3 gene (FCRL3), a novel immunoregulatory gene, have been shown to be associated with certain autoimmune diseases. This study was designed to examine whether the polymorphisms of FCRL3 are associated with susceptibility to Vogt-Koyanagi-Harada (VKH) syndrome in a Chinese population.
A case-control study was performed in 230 Chinese VKH patients and 301 healthy controls. Four single nucleotide polymorphisms (SNPs; −169C/T, −110A/G, +358C/G, and +1381A/G) in FCRL3 were detected using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). human leukocyte antigen -DR4 (HLA-DR4) and HLA-DRw53 genotyping was performed using PCR techniques.
The results showed that the frequency of haplotype CACG was significantly lower in patients when compared with that in controls (p=0.0018, corrected p [pc]=0.0288). A significantly higher frequency was found for haplotype CGGG in HLA-DR4 negative patients than in HLA-DR4 negative controls (p=9.94×10−8, Pc=1.59×10−6). There were no significant differences in the allele and genotype frequencies of the four investigated SNPs between VKH patients and controls. HLA-DR4 and HLA-DRw53 were significantly associated with VKH syndrome (p=3.21×10−16 and p=7.08×10−5, respectively). Stratification analysis according to HLA-DR4 and HLA-DRw53 did not show any association of FCRL3 polymorphisms with VKH syndrome.
Our study confirms the previous association of HLA-DR4 and HLA-DRw53 with VKH syndrome but fails to demonstrate an association between FCRL3 polymorphisms and VKH syndrome. Haplotype CACG might be a protective haplotype for VKH syndrome, and haplotype CGGG may be a risk haplotype in HLA-DR4 negative individuals.
CD4+FoxP3+ regulatory T cells (Treg) play a critical role in maintaining self tolerance and inhibiting autoimmune disease. Despite being a major focus of modern immunological investigation, many aspects of Treg biology remain unknown. In a screen for novel candidate genes involved in human Treg function, we detected the expression of an autoimmune susceptibility gene, FcRL3, in Treg but not in conventional CD4+ T cells. FcRL3 is an orphan receptor of unknown function with structural homology to classical Fc receptors. Numerous genetic studies have demonstrated a link between a single nucleotide polymorphism in the FCRL3 promoter and both overexpression of FcRL3 and autoimmune diseases such as rheumatoid arthritis. Given the critical role of Treg in suppressing autoimmunity, we sought to ascertain how expression of FcRL3 relates to the phenotype, differentiation, and function of Treg. We show here that FcRL3 is expressed on a population of thymically derived Treg that exhibits a memory phenotype and high levels of programmed cell death-1 (PD-1). Purified FcRL3+ Treg are less responsive to antigenic stimulation in the presence of IL-2 than their FcRL3− counterparts, despite intact proximal and distal IL-2 signaling as determined by phosphorylation of Stat-5 and upregulation of Bcl2. In vitro suppression assays demonstrated that FcRL3+ Treg have reduced capacity to suppress the proliferation of effector T cells. These data suggest that FcRL3 expression is associated with Treg dysfunction that may, in turn, contribute to the loss of self tolerance and the development of autoimmunity.
Fc receptor-like A (FCRLA) and FCRLB have homology to the transmembrane FCRL family members (FCRL1–6) and to the conventional receptors for the Fc portion of immunoglobulin, but uniquely are cytosolic proteins expressed in B cells. Here we describe the phenotype of Fcrlb gene targeted mice. B cell development and in vitro responses are normal; however, antibody responses to a T-dependent antigen are elevated. The gene encoding the inhibitory FcγRIIb is located nearby Fcrlb. Although Fcrlb gene targeting had no effect on the function or basal expression of FcγRIIb, its expression was reduced following activation. This abnormal regulation was due to co-inheritance of Fcgr2b and the mutant Fcrlb allele from the 129 ES cells. A promoter polymorphism in the 129/Sv Fcgr2b allele results in diminished upregulation of FcγRIIb following B cell activation. Thus, we speculate that the enhanced antibody response seen in the FCRLB-deficient mice may be due to the Fcgr2b promoter.
Fc receptor; Gene targeting; FcγRIIb; Antibody response; Germinal center
Fc receptor-like 6 (FCRL6), the most recently characterized member of the FCRL family, is a cell surface glycoprotein with tyrosine-based regulatory potential. An extensive survey of human hematopoietic tissues disclosed that FCRL6 expression by NK and T cell subpopulations increases as a function of differentiation and is remarkably restricted to mature lymphocytes with cytotoxic capability. In particular, FCRL6 distinguishes perforin-expressing CD56dim NK cells, Vδ1+ and Vδ2+ γδ T cells, effector and effector memory CD8+ T cells, and rare cytotoxic CD4+ T cells in adult tissues. Analysis of this receptor in B cell chronic lymphocytic leukemia (CLL) was also performed. FCRL6 was found to mark significantly expanded populations of cytotoxic CD8+ T, CD4+ T, and NK cells in patients with CLL. Despite sequence homology with the known Fc receptors for IgG and IgE, FCRL6 did not bind immunoglobulin. Although FCRL6 can be tyrosine-phosphorylated, its antibody-mediated ligation was unable to influence cellular activation. Collectively these results demonstrate that FCRL6 is a distinct indicator of cytotoxic effector lymphocytes that is upregulated in diseases characterized by chronic immune stimulation.
Human NK cells; Human cytotoxic T cells; Fc Receptor-like; Chronic lymphocytic leukemia
A Japanese study has described a strong association between rheumatoid arthritis and several polymorphisms located in the Fc receptor‐like 3 (FCRL3) gene, a member of a family of genes related to Fc receptors located on chromosome 1q21–23.
To evaluate the association between rheumatoid arthritis and FCLR3 polymorphisms in a large cohort of Caucasian patients with rheumatoid arthritis and healthy controls of Spanish origin. Owing to the described functional link between the FCRL3 polymorphisms and the transcription factor nuclear factor κB (NFκB), a functional polymorphism located in the NFκB1 gene was included.
734 patients with rheumatoid arthritis from Madrid and Granada, Spain, were included in the study, along with 736 healthy controls. Polymorphisms in the FCRL3 gene were studied by TaqMan technology. The −94ins/delATTG NFκB1 promoter polymorphism was analysed by fragment analysis after polymerase chain reaction with labelled primers. Genotypes were compared using 3×2 contingency tables and χ2 values.
No overall differences were found in any of the FCRL3 polymorphisms and in the NFκB1 promoter polymorphism when patients were compared with controls. However, when stratified according to NFκB1 genotypes, a susceptibility effect of FCRL3 polymorphisms was observed in patients who were heterozygotes for NFκB1 (pc = 0.003).
The FCRL3 polymorphisms associated with rheumatoid arthritis in a Japanese population are not associated per se with rheumatoid arthritis in a Spanish population. A genetic interaction was found between NFκB1 and FCRL3 in Spanish patients with rheumatoid arthritis. These findings may provide a general rationale for divergent genetic association results in different populations.
To pinpoint the exact location of the etiological variant/s present at 1q21.1 harboring FCRL1-5 and CD5L genes, we carried out a refined association study in the entire FCRL region in 1,536 patients with Graves’ disease (GD) and 1,516 sex-matched controls by imputation analysis, logistic regression, and cis-eQTL analysis. Among 516 SNPs with P<0.05 in the initial GWAS scan, the strongest signals associated with GD and correlated to FCRL3 expression were located at a cluster of SNPs including rs7528684 and rs3761959. And the allele-specific effects for rs3761959 and rs7528684 on FCRL3 expression level revealed that the risk alleles A of rs3761959 and C of rs7528684 were correlated with the elevated expression level of FCRL3 whether in PBMCs or its subsets, especially in CD19+ B cells and CD8+ T subsets. Next, the combined analysis with 5,300 GD cases and 4,916 control individuals confirmed FCRL3 was a susceptibility gene of GD in Chinese Han populations, and rs3761959 and rs7528684 met the genome-wide association significance level (Pcombined = 2.27×10−12 and 7.11×10−13, respectively). Moreover, the haplotypes with the risk allele A of rs3761959 and risk allele C of rs7528684 were associated with GD risk. Finally, our epigenetic analysis suggested the disease-associated C allele of rs7528684 increased affinity for NF-KB transcription factor. Above data indicated that FCRL3 gene and its proxy SNP rs7528684 may be involved in the pathogenesis of GD by excessive inhibiting B cell receptor signaling and the impairment of suppressing function of Tregs.
Human immunodeficiency virus (HIV) disease leads to impaired B cell and antibody responses through mechanisms that remain poorly defined. A unique memory B cell subpopulation (CD20hi/CD27lo/CD21lo) in human tonsillar tissues was recently defined by the expression of the inhibitory receptor Fc-receptor-like-4 (FCRL4). In this study, we describe a similar B cell subpopulation in the blood of HIV-viremic individuals. FCRL4 expression was increased on B cells of HIV-viremic compared with HIV-aviremic and HIV-negative individuals. It was enriched on B cells with a tissuelike memory phenotype (CD20hi/CD27−/CD21lo) when compared with B cells with a classical memory (CD27+) or naive (CD27−/CD21hi) B cell phenotype. Tissuelike memory B cells expressed patterns of homing and inhibitory receptors similar to those described for antigen-specific T cell exhaustion. The tissuelike memory B cells proliferated poorly in response to B cell stimuli, which is consistent with high-level expression of multiple inhibitory receptors. Immunoglobulin diversities and replication histories were lower in tissuelike, compared with classical, memory B cells, which is consistent with premature exhaustion. Strikingly, HIV-specific responses were enriched in these exhausted tissuelike memory B cells, whereas total immunoglobulin and influenza-specific responses were enriched in classical memory B cells. These data suggest that HIV-associated premature exhaustion of B cells may contribute to poor antibody responses against HIV in infected individuals.
Fc receptor-like A (FCRLA) is an unusual member of the extended Fc receptor family. FCRLA has homology to receptors for the Fc portion of Ig (FCR) and to other FCRL proteins. However, unlike these other family representatives, which are typically transmembrane receptors with extracellular ligand-binding domains, FCRLA has no predicted transmembrane domain or N-linked glycosylation sites and is an intracellular protein. We show by confocal microscopy and biochemical assays that FCRLA is a soluble resident endoplasmic reticulum (ER) protein, but it does not possess the amino acid sequence KDEL as an ER retention motif in its C-terminus. Using a series of deletion mutants, we found that its ER retention is most likely mediated by the amino terminal partial Ig-like domain. We have identified ER-localized Ig as the FCRLA ligand. FCRLA is unique among the large family of Fc receptors, in that it is capable of associating with multiple Ig isotypes, IgM, IgG and IgA. Among hemopoietic cells, FCRLA expression is restricted to the B lineage and is most abundant in germinal center B lymphocytes. The studies reported here demonstrate that FCRLA is more broadly expressed among human B lineage cells than originally reported; it is found at significant levels in resting blood B cells and at varying levels in all B-cell subsets in tonsil.
B lymphocyte; ER retention; Fc receptor; membrane and secretory Ig; microsomes
Chronic immune activation in HIV-infected individuals leads to accumulation of
exhausted tissue-like memory B cells. Exhausted lymphocytes display increased
expression of multiple inhibitory receptors, which may contribute to the inefficiency
of HIV-specific antibody responses. Here, we show that downregulation of B cell
inhibitory receptors in primary human B cells led to increased tissue-like memory B
cell proliferation and responsiveness against HIV. In human B cells, siRNA knockdown
of 9 known and putative B cell inhibitory receptors led to enhanced B cell
receptor–mediated (BCR-mediated) proliferation of tissue-like memory but
not other B cell subpopulations. The strongest effects were observed with the
putative inhibitory receptors Fc receptor–like–4 (FCRL4) and
sialic acid–binding Ig-like lectin 6 (Siglec-6). Inhibitory receptor
downregulation also led to increased levels of HIV-specific antibody-secreting cells
and B cell–associated chemokines and cytokines. The absence of known
ligands for FCRL4 and Siglec-6 suggests these receptors may regulate BCR signaling
through their own constitutive or tonic signaling. Furthermore, the extent of FCLR4
knockdown effects on BCR-mediated proliferation varied depending on the costimulatory
ligand, suggesting that inhibitory receptors may engage specific pathways in
inhibiting B cell proliferation. These findings on HIV-associated B cell exhaustion
define potential targets for reversing the deleterious effect of inhibitory receptors
on immune responses against persistent viral infections.
The Toll-like receptor 7 (TLR7) gene, encoded on human chromosome Xp22.3, is crucial for type I interferon production. A recent multicenter study in East Asian populations, comprising Chinese, Korean and Japanese participants, identified an association of a TLR7 single-nucleotide polymorphism (SNP) located in the 3' untranslated region (3' UTR), rs3853839, with systemic lupus erythematosus (SLE), especially in males, although some difference was observed among the tested populations. To test whether additional polymorphisms contribute to SLE in Japanese, we systematically analyzed the association of TLR7 with SLE in a Japanese female population.
A case-control association study was conducted on eight tag SNPs in the TLR7 region, including rs3853839, in 344 Japanese females with SLE and 274 healthy female controls.
In addition to rs3853839, two SNPs in intron 2, rs179019 and rs179010, which were in moderate linkage disequilibrium with each other (r2 = 0.53), showed an association with SLE (rs179019: P = 0.016, odds ratio (OR) 2.02, 95% confidence interval (95% CI) 1.15 to 3.54; rs179010: P = 0.018, OR 1.75, 95% CI 1.10 to 2.80 (both under the recessive model)). Conditional logistic regression analysis revealed that the association of the intronic SNPs and the 3' UTR SNP remained significant after we adjusted them for each other. When only the patients and controls carrying the risk genotypes at the 3' UTR SNPpositionwere analyzed, the risk of SLE was significantly increased when the individuals also carried the risk genotypes at both of the intronic SNPs (P = 0.0043, OR 2.45, 95% CI 1.31 to 4.60). Furthermore, the haplotype containing the intronic risk alleles in addition to the 3' UTR risk allele was associated with SLE under the recessive model (P = 0.016, OR 2.37, 95% CI 1.17 to 4.80), but other haplotypes were not associated with SLE.
The TLR7 intronic SNPs rs179019 and rs179010 are associated with SLE independently of the 3' UTR SNP rs3853839 in Japanese women. Our findings support a role of TLR7 in predisposition for SLE in Asian populations.
Under selective pressure from host immunity, viruses have retained genes encoding “immunoevasins” - molecules interfering with host viral recognition and clearance. Due to their binding specificities, immunoevasins can be exploited as affinity labels to identify host-encoded molecules of previously unsuspected importance in defense against the relevant class of virus. We previously described an orthopoxvirus MHC class I-like protein (OMCP) that binds with high affinity to the activating receptor NKG2D on NK and T cell subsets, implicating NKG2D in anti-orthopoxvirus immunity. Here, we report that OMCP also binds in an NKG2D-independent manner to B cells and monocytes/macrophages. We identify murine Fc receptor-like 5 (FCRL5), an orphan immunoregulatory protein highly expressed by innate B lymphocytes, as a specific receptor for OMCP. The three N-terminal Ig domains of FCRL5 are required for OMCP binding. The targeting of FCRL5 by an orthopoxvirus immunoevasin strongly implicates it in contributing to host defense against zoonotic orthopoxviruses.
The presented comprehensive review of current knowledge about genetic factors predisposing to Graves’ disease (GD) put emphasis on functional significance of observed associations. In particular, we discuss recent efforts aimed at refining diseases associations found within the HLA complex and implicating HLA class I as well as HLA-DPB1 loci. We summarize data regarding non-HLA genes such as PTPN22, CTLA4, CD40, TSHR and TG which have been extensively studied in respect to their role in GD. We review recent findings implicating variants of FCRL3 (gene for FC receptor-like-3 protein), SCGB3A2 (gene for secretory uteroglobin-related protein 1- UGRP1) as well as other unverified possible candidate genes for GD selected through their documented association with type 1 diabetes mellitus: Tenr–IL2–IL21, CAPSL (encoding calcyphosine-like protein), IFIH1(gene for interferon-induced helicase C domain 1), AFF3, CD226 and PTPN2. We also review reports on association of skewed X chromosome inactivation and fetal microchimerism with GD. Finally we discuss issues of genotype-phenotype correlations in GD.
Graves’ disease; thyroid; autoimmunity; association; HLA; non-HLA genes.
The genetic association of interferon regulatory factor 5 (IRF5) with systemic lupus erythematosus (SLE) susceptibility has been convincingly established. To gain understanding of the effect of IRF5 variation in individuals without SLE, a study was undertaken to examine whether such genetic variation predisposes to activation of the interferon α (IFNα) pathway.
Using a computer simulated approach, 14 single nucleotide polymorphisms (SNPs) and haplotypes of IRF5 were tested for association with mRNA expression levels of IRF5, IFNα and IFN-inducible genes and chemokines in lymphoblastoid cell lines (LCLs) from individuals of European (CEU), Han Chinese (CHB), Japanese (JPT) and Yoruba Nigerian (YRI) backgrounds. IFN-inducible gene expression was assessed in LCLs from children with SLE in the presence and absence of IFNα stimulation.
The major alleles of IRF5 rs13242262 and rs2280714 were associated with increased IRF5 mRNA expression levels in the CEU, CHB+JPT and YRI samples. The minor allele of IRF5 rs10488631 was associated with increased IRF5, IFNα and IFN-inducible chemokine expression in CEU (pc=0.0005, 0.01 and 0.04, respectively). A haplotype containing these risk alleles of rs13242262, rs10488631 and rs2280714 was associated with increased IRF5, IFNα and IFN-inducible chemokine expression in CEU LCLs. In vitro studies showed specific activation of IFN-inducible genes in LCLs by IFNα.
SNPs of IRF5 in healthy individuals of a number of ethnic groups were associated with increased mRNA expression of IRF5. In European-derived individuals, an IRF5 haplotype was associated with increased IRF5, IFNα and IFN-inducible chemokine expression. Identifying individuals genetically predisposed to increased IFN-inducible gene and chemokine expression may allow early detection of risk for SLE.
Systemic lupus erythematosus (SLE) is a complex autoimmune disease with a strong genetic component that determines risk. A common three single-nucleotide polymorphism (SNP) haplotype of the complement receptor 2 (CR2) gene has been associated with increased risk of SLE (Wu et al., 2007) (Douglas et al., 2009), and a less common haplotype consisting of the major allele at SNP1 and minor alleles at SNP2 and 3 confers protection (Douglas et al., 2009). SNP1 (rs3813946), which is located in the 5´ untranslated region (UTR) of the CR2 gene, altered transcriptional activity of a CR2 promoter-luciferase reporter gene construct transiently transfected into a B cell line (Wu et al., 2007) and had an independent effect in the protective haplotype (Douglas et al., 2009). In this study, we show that this SNP alters transcriptional activity in a transiently transfected non B-cell line as well as in stably transfected cell lines, supporting its relevance in vivo. Furthermore, the allele at this SNP affects chromatin accessibility of the surrounding sequence and transcription factor binding. These data confirm the effects of rs3813946 on CR2 transcription, identifying the 5´UTR to be a novel regulatory element for the CR2 gene in which variation may alter gene function and modify the development of lupus.
Human; B cells; Systemic Lupus Erythematosus; Gene Regulation; Transcription Factors; Complement Receptor 2
Protein tyrosine phosphatase non-receptor type 22 (PTPN22) is a negative regulator of T-cell activation associated with several autoimmune diseases, including systemic lupus erythematosus (SLE). Missense rs2476601 is associated with SLE in individuals with European ancestry. Since the rs2476601 risk allele frequency differs dramatically across ethnicities, we assessed robustness of PTPN22 association with SLE and its clinical sub-phenotypes across four ethnically diverse populations. Ten SNPs were genotyped in 8220 SLE cases and 7369 controls from in European-Americans (EA), African-Americans (AA), Asians (AS), and Hispanics (HS). We performed imputation-based association followed by conditional analysis to identify independent associations. Significantly associated SNPs were tested for association with SLE clinical sub-phenotypes, including autoantibody profiles. Multiple testing was accounted for by using false discovery rate. We successfully imputed and tested allelic association for 107 SNPs within the PTPN22 region and detected evidence of ethnic-specific associations from EA and HS. In EA, the strongest association was at rs2476601 (P = 4.7×10−9, OR = 1.40 (95% CI = 1.25–1.56)). Independent association with rs1217414 was also observed in EA, and both SNPs are correlated with increased European ancestry. For HS imputed intronic SNP, rs3765598, predicted to be a cis-eQTL, was associated (P = 0.007, OR = 0.79 and 95% CI = 0.67–0.94). No significant associations were observed in AA or AS. Case-only analysis using lupus-related clinical criteria revealed differences between EA SLE patients positive for moderate to high titers of IgG anti-cardiolipin (aCL IgG >20) versus negative aCL IgG at rs2476601 (P = 0.012, OR = 1.65). Association was reinforced when these cases were compared to controls (P = 2.7×10−5, OR = 2.11). Our results validate that rs2476601 is the most significantly associated SNP in individuals with European ancestry. Additionally, rs1217414 and rs3765598 may be associated with SLE. Further studies are required to confirm the involvement of rs2476601 with aCL IgG.