The P2X<Subscript>7</Subscript>receptor is a candidate product of murine and human lupus susceptibility loci: a hypothesis and comparison of murine allelic products

Systemic lupus erythematosus and its murine equivalent, modelled in the New Zealand Black and New Zealand White (NZB × NZW)F₁ hybrid strain, are polygenic inflammatory diseases, probably reflecting an autoimmune response to debris from cells undergoing programmed cell death. Several human and murine loci contributing to disease have been defined. The present study asks whether the proinflammatory purinergic receptor P2X₇, an initiator of a form of programmed cell death known as aponecrosis, is a candidate product of murine and human lupus susceptibility loci. One such locus in (NZB × NZW)F₁ mice is lbw3, which is situated at the distal end of NZW chromosome 5. We first assess whether NZB mice and NZW mice carry distinct alleles of the P2RX ₇ gene as expressed by common laboratory strains, which differ in sensitivity to ATP stimulation. We then compare the responses of NZB lymphocytes, NZW lymphocytes and (NZB × NZW)F₁ lymphocytes to P2X₇ stimulation. NZB and NZW parental strains express the distinct P2X₇-L and P2X₇-P alleles of P2RX ₇, respectively, while lymphocytes from these and (NZB × NZW)F₁ mice differ markedly in their responses to P2X₇ receptor stimulation. NZB mice and NZW mice express functionally distinct alleles of the proinflammatory receptor, P2X₇. We show that current mapping suggests that murine and human P2RX ₇ receptor genes lie within lupus susceptibility loci lbw3 and SLEB4, and we argue that these encode a product with the functional characteristics consistent with a role in lupus. Furthermore, we argue that aponecrosis as induced by P2X₇ is a cell death mechanism with characteristics that potentially have particular relevance to disease pathogenesis.     

Susceptibility to immunosuppression by ultraviolet B radiation in the mouse

Irradiation with ultraviolet B (UVB; 290–320 nm) initiates systemic immunosuppression of contact hypersensitivity (CHS). UV dose-responses for suppression of CHS to trinitrochlorobenzene were established in 18 strains of inbred mice. Three phenotypes with significantly different susceptibilities to UV suppression were identified. The phenotypes were: high (HI) susceptibility, 50% suppression with 0.7–2.3 kJ/m² UV (C57BL/6, C57BL/10, and C57L and NZB females); low (LO) susceptibility, 50% suppression with 9.6–12.3 kJ/m² UV (BALB/c, AKR, SJL and NZW), and intermediate (INT) susceptibility, 50% suppression with 4.7–6.9 kJ/m² UV (DBA/2, C57BR, C3H/HeJ, C3H/HeN, CBA/N and A/J). UV suppression was not correlated with skin pigmentation or with the magnitude of the CHS response in non-irradiated animals. Major histocompatibility complex (MHC) haplotype was not correlated with UV suppression in MHC congenic strains B10.D2/oSnJ, B10.D2/nSnJ, B10.BR/SgSnJ, and A.BY/SnJ. There were no sex differences in UV suppression in BALB/c, C57BL/6, or NZW animals. In the autoimmune NZB strain, however, male mice (LO) were seven times less sensitive to UV suppression than NZB female mice (HI). Both sexes of (NZB × NZW)F₁ and (NZW × NZB)F₁ mice were HI, supporting dominance of HI over LO. Thus there are genetic factors and interacting sex-limited factors determining susceptibility to UV suppression. These findings may be of relevance to UV-related diseases such as photosensitive lupus and skin cancer. Correspondence to: F. P. Noonan.     

CD4+ T cells from (New Zealand Black x New Zealand White)F1 lupus mice and normal mice immunized against apoptotic nucleosomes recognize similar Th cell epitopes in the C terminus of histone H3

We have previously reported that peptide 88-99 of histone H4 represents a minimal T cell epitope recognized by Th cells from nonautoimmune BALB/c (H-2(d/d)) mice immunized with nucleosomes. In this study, we tested a panel of overlapping peptides spanning the whole sequences of H4 and H3 for recognition by CD4(+) T cells from unprimed (New Zealand Black (NZB) x New Zealand White (NZW))F(1) lupus mice (H-2(d/z)). None of the 11 H4 peptides was recognized by CD4(+) T cells from (NZB x NZW)F(1) mice. In contrast, these cells proliferated and secreted IL-2, IL-10, and IFN-gamma upon ex vivo stimulation with H3 peptides representing sequences 53-70, 64-78, and 68-85. Peptides 56-73 and 61-78 induced the production of IFN-gamma and IL-10, respectively, without detectable proliferation, suggesting that they may act as partial agonist of the TCR. Th cells from unprimed BALB/c mice and other lupus-prone mice such as SNF(1) (H-2(d/q)) and MRL/lpr (H-2(k/k)) mice did not recognize any peptides present within the H3 region 53-85. We further demonstrated that immunization of normal BALB/c mice with syngeneic liver nucleosomes and spleen apoptotic cells, but not with nonapoptotic syngeneic cells, induced Th cell responses against several peptides of the H3 region 53-85. Moreover, we found that this conserved region of H3, which is accessible at the surface of nucleosomes, is targeted by Abs from (NZB x NZW)F(1) mice and lupus patients, and contains motifs recognized by several distinct HLA-DR molecules. It might thus be important in the self-tolerance breakdown in lupus.     

Aberrant genetic control of invariant TCR-bearing NKT cell function in New Zealand mouse strains: possible involvement in systemic lupus erythematosus pathogenesis

Both suppressive and promoting roles of NKT cells have been reported in the pathogenesis of systemic lupus erythematosus (SLE). Herein, we found that although New Zealand mice have normal frequencies of NKT cells, their in vitro potential to produce IL-4 and IFN-gamma in response to alpha-galactosylceramide was remarkably impaired in New Zealand Black (NZB) mice prone to mild SLE, while production was highly up-regulated in nonautoimmune New Zealand White (NZW) mice and at intermediate levels in (NZB x NZW)F(1) mice, which are prone to severe SLE. Because this aberration is evident in young mice before disease onset, genetic mechanisms are thought to be involved. Genome-wide quantitative trait locus analysis and association studies revealed that a locus linked to D11Mit14 on chromosome 11 may be involved in the difference in cytokine-producing potential between NZB and NZW NKT cells. Additionally, (NZB x NZW)F(1) x NZB backcross progeny with the NZW genotype for D11Mit14 showed significantly increased frequencies of age-associated SLE phenotypes, such as high serum levels of IgG, IgG anti-DNA Abs, and lupus nephritis. In coculture studies, alpha-galactosylceramide-stimulated NKT cells from NZW and (NZB x NZW)F(1) mice, but not from NZB mice, showed significantly enhanced Ig synthesis by B cells. These findings suggest that the D11Mit14-linked NZW locus may contribute to the development of SLE in (NZB x NZW)F(1) mice through a mechanism that up-regulates NKT cell function. Thus, this NZW allele may be a candidate of the NZW modifiers that act to promote (NZB x NZW)F(1) disease.     

IL-17RA signaling amplifies antibody-induced arthritis

Objective

To investigate the role of IL-17RA signaling in the effector phase of inflammatory arthritis using the K/BxN serum-transfer model.

Methods

Wild-type and Il17ra^−/− mice were injected with serum isolated from arthritic K/BxN mice and their clinical score was recorded daily. Mice were also harvested on days 12 and 21 and ankles were analyzed for cytokine and chemokine mRNA expression by qPCR on day 12 and for bone and cartilage erosions by histology on day 21, respectively. The induction of cytokine and chemokine expression levels by IL-17A in synovial-like fibroblasts was also analyzed using qPCR.

Results

Il17ra^−/− mice were partially protected from clinical signs of arthritis and had markedly fewer cartilage and bone erosions. The expression of several pro-inflammatory mediators, including the chemokines KC/CXCL1, MIP-2/CXCL2, LIX/CXCL5 MIP-1γ/CCL9, MCP-3/CCL7, MIP-3α/CCL20, the cytokines IL-1β, IL-6, RANKL and the matrix metalloproteinases MMP2, MMP3, and MMP13 were decreased in the ankles of Il17ra^−/− mice compared to wild-type mice. Many of these proinflammatory genes attenuated in the ankles of Il17ra^−/− mice were shown to be directly induced by IL-17A in synovial fibroblasts in vitro.

Conclusions

IL-17RA signaling plays a role as an amplifier of the effector phase of inflammatory arthritis. This effect is likely mediated by direct activation of synovial fibroblasts by IL-17RA to produce multiple inflammatory mediators, including chemokines active on neutrophils. Therefore, interrupting IL-17RA signaling maybe a promising pharmacological target for the treatment of inflammatory arthritis.     

Genetic complementation in female (BXSB x NZW)F2 mice

F(1) hybrids among New Zealand Black (NZB), New Zealand White (NZW), and BXSB lupus-prone strains develop accelerated autoimmunity in both sexes regardless of the specific combination. To identify BXSB susceptibility loci in the absence of the Y chromosome accelerator of autoimmunity (Yaa) and to study the genetics of this complementation, genome-wide quantitative trait locus (QTL) mapping was performed on female (BXSB x NZW)F(2) mice. Six QTL were identified on chromosomes 1, 4, 5, 6, 7, and 17. Survival mapped to chromosomes 5 and 17, anti-chromatin Ab to chromosomes 4 and 17, glomerulonephritis to chromosomes 6 and 17, and splenomegaly to chromosomes 1, 7, and 17. QTL on chromosomes 4 and 6 were new and designated as Lxw1 and -2, respectively. Two non-MHC QTL (chromosomes 1 and 4) were inherited from the BXSB and the rest were NZW-derived, including two similar to previously defined loci. Only two of 11 previously defined non-MHC BXSB QTL using male (Yaa(+)) crosses were implicated, suggesting that some male-defined BXSB QTL may require coexpression of the Yaa. Findings from this and other studies indicate that BXSB and NZB backgrounds contribute completely different sets of genes to complement NZW mice. Identification of susceptibility genes and complementing genes in several lupus-prone strain combinations will be important for defining the epistatic effects and background influences on the heterogeneous genetic factors responsible for lupus induction.     

A novel susceptibility locus on chromosome 2 in the (New Zealand Black x New Zealand White)F1 hybrid mouse model of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is inherited as a complex polygenic trait. (New Zealand Black (NZB) x New Zealand White (NZW)) F(1) hybrid mice develop symptoms that remarkably resemble human SLE, but (NZB x PL/J)F(1) hybrids do not develop lupus. Our study was conducted using (NZW x PL/J)F(1) x NZB (BWP) mice to determine the effects of the PL/J and the NZW genome on disease. Forty-five percent of BWP female mice had significant proteinuria and 25% died before 12 mo of age compared with (NZB x NZW)F(1) mice in which >90% developed severe renal disease and died before 12 mo. The analysis of BWP mice revealed a novel locus (chi(2) = 25.0; p < 1 x 10(-6); log of likelihood = 6.6 for mortality) designated Wbw1 on chromosome 2, which apparently plays an important role in the development of the disease. We also observed that both H-2 class II (the u haplotype) and TNF-alpha (TNF(z) allele) appear to contribute to the disease. A suggestive linkage to proteinuria and death was found for an NZW allele (designated Wbw2) telomeric to the H-2 locus. The NZW allele that overlaps with the previously described locus Sle1c at the telomeric part of chromosome 1 was associated with antinuclear autoantibody production in the present study. Furthermore, the previously identified Sle and Lbw susceptibility loci were associated with an increased incidence of disease. Thus, multiple NZW alleles including the Wbw1 allele discovered in this study contribute to disease induction, in conjunction with the NZB genome, and the PL/J genome appears to be protective.     

IL-10 Production Is Critical for Sustaining the Expansion of CD5+ B and NKT Cells and Restraining Autoantibody Production in Congenic Lupus-Prone Mice

The development and progression of systemic lupus erythematosus is mediated by the complex interaction of genetic and environmental factors. To decipher the genetics that contribute to pathogenesis and the production of pathogenic autoantibodies, our lab has focused on the generation of congenic lupus-prone mice derived from the New Zealand Black (NZB) strain. Previous work has shown that an NZB-derived chromosome 4 interval spanning 32 to 151 Mb led to expansion of CD5⁺ B and Natural Killer T (NKT) cells, and could suppress autoimmunity when crossed with a lupus-prone mouse strain. Subsequently, it was shown that CD5⁺ B cells but not NKT cells derived from these mice could suppress the development of pro-inflammatory T cells. In this paper, we aimed to further resolve the genetics that leads to expansion of these two innate-like populations through the creation of additional sub-congenic mice and to characterize the role of IL-10 in the suppression of autoimmunity through the generation of IL-10 knockout mice. We show that expansion of CD5⁺ B cells and NKT cells localizes to a chromosome 4 interval spanning 91 to 123 Mb, which is distinct from the region that mediates the majority of the suppressive phenotype. We also demonstrate that IL-10 is critical to restraining autoantibody production and surprisingly plays a vital role in supporting the expansion of innate-like populations.     

Analysis of MHC class II genes in the susceptibility to lupus in New Zealand mice

Hybrids of New Zealand Black (NZB) and New Zealand White (NZW) mice spontaneously develop a disease similar to human systemic lupus erythematosus. MHC and non-MHC genes contribute to disease susceptibility in this murine model. Multiple studies have shown that the NZW H2z locus is strongly associated with the development of lupus-like disease in these mice. The susceptibility gene(s) within H2z is not known, but different lines of evidence have pointed to class II MHC genes, either H2-E or H2-A (Ez or Az in NZW). Recent studies from our laboratory showed that Ez does not supplant H2z in the contribution to lupus-like disease. In the present work we generated C57BL/10 (B10) mice transgenic for Aaz and Abz genes (designated B10.Az mice) and used a (B10.Az x NZB)F1 x NZB backcross to assess the contributions of Az genes to disease. A subset of backcross mice produced high levels of IgG autoantibodies and developed severe nephritis. However, no autoimmune phenotype was linked to the Az transgenes. Surprisingly, in the same backcross mice, inheritance of H2b from the nonautoimmune B10 strain was strongly linked with both autoantibody production and nephritis. Taken together with our previous Ez studies, the present work calls into question the importance of class II MHC genes for lupus susceptibility in this model and provides new insight into the role of MHC in lupus-like autoimmunity.     

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

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

Activation and IL-10 production of specific CD4+ T cells are regulated by IL-27 during chronic infection with Plasmodium chabaudi

IL-27, a regulatory cytokine, plays critical roles in the prevention of immunopathology during Plasmodium infection. We examined these roles in the immune responses against Plasmodium chabaudi infection using the Il-27ra^−/− mice. While IL-27 was expressed at high levels during the early phase of the infection, enhanced CD4⁺ T cell function and reduction in parasitemia were observed mainly during the chronic phase in the mutant mice. In mice infected with P. chabaudi and cured with drug, CD4⁺ T cells in the Il-27ra^−/− mice exhibited enhanced CD4⁺ T-cell responses, indicating the inhibitory role of IL-27 on the protective immune responses. To determine the role of IL-27 in detail, we performed CD4⁺ T-cell transfer experiments. The Il-27ra^−/− and Il27p28^−/− mice were first infected with P. chabaudi and then cured using drug treatment. Plasmodium-antigen primed CD4⁺ T cells were prepared from these mice and transferred into the recipient mice, followed by infection with the heterologous parasite P. berghei ANKA. Il-27ra^−/− CD4⁺ T cells in the infected recipient mice did not produce IL-10, indicating that IL-10 production by primed CD4⁺ T cells is IL-27 dependent. Il27p28^−/− CD4⁺ T cells that were primed in the absence of IL-27 exhibited enhanced recall responses during the challenge infection with P. berghei ANKA, implying that IL-27 receptor signaling during the primary infection affects recall responses in the long-term via the regulation of the memory CD4⁺ T cell generation. These features highlighted direct and time-transcending roles of IL-27 in the regulation of immune responses against chronic infection with Plasmodium parasites.     

Macroautophagy is deregulated in murine and human lupus T lymphocytes

Macroautophagy was recently shown to regulate both lymphocyte biology and innate immunity. In this study we sought to determine whether a deregulation of autophagy was linked to the development of autoimmunity. Genome-wide association studies have pointed out nucleotide polymorphisms that can be associated with systemic lupus erythematosus, but the potential role of autophagy in the initiation and/or development of this syndrome is still unknown. Here, we provide first clues of macroautophagy deregulation in lupus. By the use of LC3 conversion assays and electron microscopy experiments, we observed that T cells from two distinct lupus-prone mouse models, i.e., MRL^lpr/lpr and (NZB/NZW)F1, exhibit high loads of autophagic compartments compared with nonpathologic control CBA/J and BALB/c mice. Unlike normal mice, autophagy increases with age in murine lupus. In vivo lipopolysaccharide stimulation in CBA/J control mice efficiently activates T lymphocytes but fails to upregulate formation of autophagic compartments in these cells. This argues against a deregulation of autophagy in lupus T cells solely resulting from an acute inflammation injury. Autophagic vacuoles quantified by electron microscopy are also found to be significantly more frequent in T cells from lupus patients compared with healthy controls and patients with non-lupus autoimmune diseases. This elevated number of autophagic structures is not distributed homogeneously and appears to be more pronounced in certain T cells. These results suggest that autophagy could regulate the survival of autoreactive T cell during lupus, and could thus lead to design new therapeutic options for lupus.     

A Cmv2 QTL on chromosome X affects MCMV resistance in New Zealand male mice

NK cell-mediated resistance to viruses is subject to genetic control in humans and mice. Here we used classical and quantitative genetic strategies to examine NK-mediated murine cytomegalovirus (MCMV) control in genealogically related New Zealand white (NZW) and black (NZB) mice. NZW mice display NK cell-dependent MCMV resistance while NZB NK cells fail to limit viral replication after infection. Unlike Ly49H⁺ NK resistance in C57BL/6 mice, NZW NK-mediated MCMV control was Ly49H-independent. Instead, MCMV resistance in NZW (Cmv2) involves multiple genetic factors. To establish the genetic basis of Cmv2 resistance, we further characterized a major chromosome X-linked resistance locus (DXMit216) responsible for innate MCMV control in NZW × NZB crosses. We found that the DXMit216 locus affects early MCMV control in New Zealand F₂ crosses and demonstrate that the NZB-derived DXMit216 allele enhances viral resistance in F₂ males. The evolutionary conservation of the DXMit216 region in mice and humans suggests that a Cmv2-related mechanism may affect human antiviral responses. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

IFN-alpha induces early lethal lupus in preautoimmune (New Zealand Black x New Zealand White) F1 but not in BALB/c mice

Recent studies indicate that IFN-alpha is involved in pathogenesis of systemic lupus erythematosus. However, direct proof that IFN-alpha is not only necessary, but also sufficient to induce lupus pathogenicity is lacking. In this study, we show that in vivo adenovector-mediated delivery of murine IFN-alpha results in preautoimmune (New Zealand Black (NZB) x New Zealand White (NZW))F(1), but not in normal, mice, in a rapid and severe disease with all characteristics of systemic lupus erythematosus. Anti-dsDNA Abs appeared as soon as day 10 after initiation of IFN-alpha treatment. Proteinuria and death caused by glomerulonephritis occurred in all treated mice within, respectively, approximately 9 and approximately 18 wk, at a time when all untreated (NZB x NZW)F(1) did not show any sign of disease. IFN-alpha in vivo induced an overexpression of B lymphocyte stimulator in circulation at similar levels in both the preautoimmune and the normal mouse strains. All effects elicited by IFN-alpha were dose dependent. (NZB x NZW)F(1) infused with purified murine IFN-alpha also showed acceleration of lupus. Thus, prolonged expression of IFN-alpha in vivo induces early lethal lupus in susceptible animals.     

Production of high affinity autoantibodies in autoimmune New Zealand Black/New Zealand white F1 mice targeted with an anti-DNA heavy chain

Lupus-prone, anti-DNA, heavy (H) chain "knock-in" mice were obtained by backcrossing C57BL/6 mice, targeted with a rearranged H chain from a VH11(S107)-encoded anti-DNA hybridoma (D42), onto the autoimmune genetic background of New Zealand Black/New Zealand White (NZB/NZW) F1 mice. The targeted female mice developed typical lupus serologic manifestations, with the appearance of transgenic IgM anti-DNA autoantibodies at a young age (2-3 mo) and high affinity, somatically mutated IgM and IgG anti-DNA Abs at a later age (6-7 mo). However, they did not develop clinical, lupus-associated glomerulonephritis and survived to at least 18 mo of age. L chain analysis of transgenic anti-DNA Abs derived from diseased NZB/NZW mouse hybridomas showed a very restricted repertoire of Vkappa utilization, different from that of nonautoimmune (C57BL/6 x BALB/c)F1 transgenic anti-DNA Abs. Strikingly, a single L chain was repetitively selected by most anti-DNA, transgenic NZB/NZW B cells to pair with the targeted H chain. This L chain had the same Vkappa-Jkappa rearrangement as that expressed by the original anti-DNA D42 hybridoma. These findings indicate that the kinetics of the autoimmune serologic manifestations are similar in wild-type and transgenic lupus-prone NZB/NZW F1 mice and suggest that the breakdown of immunologic tolerance in these mice is associated with the preferential expansion and activation of B cell clones expressing high affinity anti-DNA H/L receptor combinations.     

Cutting edge: a role for CD1 in the pathogenesis of lupus in NZB/NZW mice

Since anti-CD1 TCR transgenic T cells can activate syngeneic B cells via CD1 to secrete IgM and IgG and induce lupus in BALB/c mice, we studied the role of CD1 in the pathogenesis of lupus in NZB/NZW mice. Approximately 20% of B cells from the spleens of NZB/NZW mice expressed high levels of CD1 (CD1high B cells). The latter subset spontaneously produced large amounts of IgM anti-dsDNA Abs in vitro that was up to 25-fold higher than that of residual CD1int/low B cells. T cells in the NZB/NZW spleen proliferated vigorously to the CD1-transfected A20 B cell line, but not to the parent line. Treatment of NZB/NZW mice with anti-CD1 mAbs ameliorated the development of lupus. These results suggest that the CD1high B cells and their progeny are a major source of autoantibody production, and activation of B cells via CD1 may play an important role in the pathogenesis of lupus.     

The −1082A/G polymorphism in the Interleukin-10 gene and the risk of rheumatoid arthritis: A meta-analysis

A large number of studies have shown that the −1082A/G polymorphism (rs1800896) in the Interleukin-10 gene (IL-10) is implicated in the susceptibility to rheumatoid arthritis (RA). However, the results are inconsistent and inconclusive. The aim of this study is to analyze the association between the −1082A/G polymorphism in the IL-10 gene and the RA risk by meta-analysis. A total of 1480 cases and 1413 controls in 10 case–control studies were included in this meta-analysis. The results indicated that the G allele carriers (GG + GA) had a 25% decreased risk of RA, when compared with the homozygote AA (odds ratio (OR) = 0.75, 95% confidence interval (CI): 0.59–0.93). In the analysis in Europeans, significant decreased risks were associated with the G allele carriers (OR = 0.73 and 95% CI: 0.57–0.93 for GG + GA vs. AA). The results from this meta-analysis provide evidence for the association between the IL-10 −1082A/G polymorphism and the risk of RA. To further evaluate gene × gene and gene × environment interactions between the polymorphisms in the IL-10 gene and RA risk, more studies with large groups of patients are required.     

Association of polymorphisms in the human IL-10 and IL-18 genes with rheumatoid arthritis

The decrease of anti-inflammatory cytokine and increase of pro-inflammatory cytokine was observed in rheumatoid arthritis (RA). Interleukin-10 (IL-10), a potent anti-inflammatory cytokine, has been demonstrated to suppress joint swelling and deformation in RA animal model. Interleukin-18 (IL-18), a widely distributed pro-inflammatory cytokine, induces the production of IFN-γ, activate NK cells, and promote inflammation. Recent studies demonstrated that the serum IL-10 and IL-18 levels may be influenced by genetics and related to susceptibility to several autoimmune diseases. In the present study, using polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) and DNA sequencing techniques, we analyzed the genotype and allele distributions of two single nucleotide polymorphisms (SNP) loci in the promoter region of IL-10 and IL-18 genes (IL-10-592 A/C and IL-18-607 A/C loci, respectively). Our results indicated that IL-10-592 allelic and genotypic frequencies were significantly different between the RA patients and normal subjects (P < 0.05). In addition, significant differences of IL-10-592 allelic and genotypic frequencies were also detected between the patients with or without anti-cyclic citrullinated peptide antibody (anti-CCP) (P < 0.05). In contrast, allelic and genotypic frequencies of IL-18-607 did not show significant difference between RA patients and normal subjects (P > 0.05) or between anti-CCP-positive and anti-CCP-negative RA patients (P > 0.05). Furthermore, ELISA detection of IL-10 and IL-18 serum levels revealed that the genotype of IL-10-592 was associated with IL-10 serum level (P < 0.05), but the genotype and allele frequency of IL-18-607 was not associated with IL-18 serum level (P > 0.05). Taken together, our findings provide new insight for the polymorphism of IL-10 gene in the pathogenesis of RA.     

Separation of the New Zealand Black genetic contribution to lupus from New Zealand Black determined expansions of marginal zone B and B1a cells

The F(1) hybrid of New Zealand Black (NZB) and New Zealand White (NZW) mice develop an autoimmune disease similar to human systemic lupus erythematosus. Because NZB and (NZB x NZW)F(1) mice manifest expansions of marginal zone (MZ) B and B1a cells, it has been postulated that these B cell abnormalities are central to the NZB genetic contribution to lupus. Our previous studies have shown that a major NZB contribution comes from the Nba2 locus on chromosome 1. C57BL/6 (B6) mice congenic for Nba2 produce antinuclear Abs, and (B6.Nba2 x NZW)F(1) mice develop elevated autoantibodies and nephritis similar to (NZB x NZW)F(1) mice. We studied B cell populations of B6.Nba2 mice to better understand the mechanism by which Nba2 leads to disease. The results showed evidence of B cell activation early in life, including increased levels of serum IgM, CD69(+) B cells, and spontaneous IgM production in culture. However, B6.Nba2 compared with B6 mice had a decreased percentage of MZ B cells in spleen, and no increase of B1a cells in the spleen or peritoneum. Expansions of these B cell subsets were also absent in (B6.Nba2 x NZW)F(1) mice. Among the strains studied, B cell expression of beta(1) integrin correlated with differences in MZ B cell development. These results show that expansions of MZ B and B1a cells are not necessary for the NZB contribution to lupus and argue against a major role for these subsets in disease pathogenesis. The data also provide additional insight into how Nba2 contributes to lupus.