Association of a single nucleotide polymorphism in the SH2D1A intronic region with systemic lupus erythematosus.

SH2D1A, also known as signaling lymphocytic activation molecule (SLAM)-associated protein (SAP), is an adaptor protein. Recently, it was reported that SAP deficient mice were protected from systemic lupus erythematosus (SLE). In this study, we postulated SH2D1A gene to be a candidate susceptibility gene for SLE and analyzed its association with SLE. A case-control association study was conducted on 5 tag single nucleotide polymorphisms (SNPs) in SH2D1A region in 506 Japanese female SLE patients and 330 healthy female controls. The luciferase assay was performed to determine the functional role of the SNP associated with SLE. One SNP in the intron 2, rs2049995, showed association with SLE (p=0.0110, odds ratio (OR) 1.97, 95% confidence interval (CI) 1.16-3.34, under the dominant model). The association of rs2049995 seemed to be stronger in the subset with the age of onset less than 20 years (p=0.0067, OR 2.65, 95% CI 1.28-5.46). Functional evaluation of rs2049995 showed that reporter gene activity was increased 1.9-fold for the susceptible allele compared with the resistant allele. An intronic SNP of SH2D1A is associated with SLE.

Association of PHRF1-IRF7 region polymorphism with clinical manifestations of systemic lupus erythematosus in a Japanese population.

Interferon regulatory factor 7 (IRF7) has an essential role in the production of type I interferon. Although recent studies detected association of a single nucleotide polymorphism (SNP) rs4963128 in PHD and ring finger domains 1 (PHRF1)/KIAA1542, located closely to IRF7, and IRF7 rs1131665 (glutamine (Gln) 412 arginine (Arg)) with systemic lupus erythematosus (SLE), causal variants have not been established. In this study, we resequenced exons and introns of IRF7 to screen for all common polymorphisms, and examined whether they were associated with SLE in 416 Japanese patients with SLE and 505 healthy controls. We also tested whether the association of PHRF1 rs4963128 with SLE was replicated in a Japanese population. None of the IRF7 polymorphisms was associated with SLE. PHRF1 rs4963128T was not significantly associated with occurrence of SLE either; however, this allele was significantly increased in SLE with anti-Sm antibodies (6.8%) as compared with healthy controls (3.1%, P = 0.014, odds ratio [OR] 2.31) and SLE without anti-Sm antibodies (3.3%, P =0.041, OR 2.12). This allele was also increased in SLE with renal disorder (5.1%) as compared with those without renal disorder (2.4%, P = 0.047, OR 2.17). These results confirmed recently reported association of PHRF1 rs4963128T with anti-Sm antibody positive SLE in African-American populations, and supported the role of PHRF1-IRF7 region in the genetics of SLE.

Association of LILRA2 (ILT1, LIR7) splice site polymorphism with systemic lupus erythematosus and microscopic polyangiitis.

Leukocyte immunoglobulin-like receptors (LILRs) are inhibitory, stimulatory or soluble receptors encoded within the leukocyte receptor complex. Some LILRs are extensively polymorphic, and exhibit evidence for balancing selection and association with disease susceptibility. LILRA2 (LIR7/ILT1) is an activating receptor highly expressed in inflammatory tissues, and is involved in granulocyte and macrophage activation. In this study, we examined the association of LILRA2 and adjacently located LILRA1 with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and microscopic polyangiitis (MPA). Polymorphism screening detected a LILRA2 SNP (rs2241524 G>A) that disrupts splice acceptor site of intron 6. Case-control association studies on 273 Japanese SLE, 296 RA, 50 MPA and 284 healthy individuals revealed increase of genotype A/A in SLE (12.1%, odds ratio (OR) 1.82, 95% confidence interval (CI) 1.02-3.24, P=0.041) and in MPA (16.0%, OR 2.52, 95% CI 1.07-5.96, P=0.049) compared with healthy individuals (7.0%). The risk allele caused an activation of a cryptic splice acceptor site that would lead to a novel LILRA2 isoform lacking three amino acids in the linker region (Delta 419-421). Flow cytometry indicated that this isoform was expressed on the surface of monocytes. These findings suggested that LILRA2 Delta 419-421 isoform encoded by the splice site SNP may play a role in SLE and MPA.

Role of APRIL (TNFSF13) polymorphisms in the susceptibility to systemic lupus erythematosus in Japanese.

OBJECTIVES: A polymorphism of APRIL, c.199G > A (Gly67Arg), has been reported to be associated with systemic lupus erythematosus (SLE) in Japanese. To identify the causative polymorphism, we screened for polymorphisms of APRIL as well as TWEAK (TNFSF12), a closely located gene that generates a fusion protein TWE-PRIL by intergenic splicing. Association of APRIL and TWEAK with rheumatoid arthritis (RA) was examined in parallel. METHODS: Polymorphisms were screened by direct sequencing. Association was analysed by case-control analysis using 266 SLE, 298 RA and 208 healthy individuals. Allele-specific difference in the mRNA level was examined using RNA difference plot analysis. Serum APRIL level was measured by ELISA. RESULTS: The protective effect of APRIL c.199A/A homozygotes in SLE was replicated (odds ratio 0.50, 95% confidence interval 0.30-0.83, P = 0.0073; pooled P = 0.0001, Pcorr = 0.007). In addition, association of c.287A > G (Asn96Ser, P = 0.0064, allele frequency) and c.*263C > T (3' untranslated region, P = 0.025, allele frequency) was detected. c.199G-c.287A (67Gly-96Asn) haplotype was found to confer risk for SLE, while c.199A-c.287G (67Arg-96Ser) was protective. Association of TWEAK was observed neither for SLE nor RA. APRIL mRNA was increased in SLE-associated c.*263T allele. In addition, serum APRIL was undetectable in all six healthy controls homozygous for the protective c.199A-c.287G haplotype (P = 0.015). CONCLUSIONS: In addition to replicating the protective role of APRIL c.199A/A, two additional SNPs in APRIL were found to be associated with SLE. Presence of a protective haplotype and a risk haplotype was demonstrated. The mechanism of association was suggested to be altered expression at the protein and mRNA levels.

The effect of methotrexate (MTX) on expression of signalling lymphocytic activation molecule (SLAM) in patients with rheumatoid arthritis (RA) and its role in the regulation of cytokine production.

OBJECTIVE: To investigate the effect of methotrexate (MTX) on cytokine production by activated CD4+ T-cells in patients with rheumatoid arthritis (RA). METHODS: The effect of MTX on intracellular expression of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4), and cell surface expression of signalling lymphocytic activation molecule (SLAM) from freshly isolated peripheral blood mononuclear cells (PBMCs), and after in vitro culture with or without MTX, was analysed with flow cytometry in 18 patients with RA and 20 healthy controls. RESULTS: Intracellular expression of IFN-gamma and IL-4 on freshly isolated CD4+ T-cells was significantly higher in patients with RA than in the controls (p<0.05). Intracellular expression of both IFN-gamma and IL-4 after culture with MTX was significantly lower than those after culture without MTX in patients with RA. Although no significant difference was observed in SLAM expression on freshly isolated CD4+ T-cells between patients with RA and the controls, MTX significantly decreased SLAM expression on both activated IFN-gamma+ and IL-4+CD4+ T-cells in patients with RA. CONCLUSION: In vitro modulation of the cytokine network by MTX, IFN-gamma, and IL-4 is one of the major targets for MTX, and production of IFN-gamma and IL-4 by PBMCs may be suppressed by SLAM on activated CD4+ T-cell in patients with RA.

Expression and activity analyses of CTLA4 in peripheral blood lymphocytes in systemic lupus erythematosus patients.

The objective of this study was to determine the expression and activity of CTLA4 in T-cells of systemic lupus erythematosus (SLE) patients. Expression of CTLA4 on freshly isolated peripheral blood T-cells was evaluated in 33 SLE patients and 25 controls using flow cytometry. The T-cells from 19 SLE patients and 22 controls were stimulated and cultured with Chinese hamster ovary cells expressing CD80 (CHO-CD80) or with CHO cells. T-cell proliferation was determined with [3H] thymidine incorporation (CPM), and the inhibitory effect of CTLA4 on T-cell proliferation was evaluated by the ratio of CPM for T-cells with CHO-CD80 cells to that of T-cells with CHO cells (the CHO-CD80/CHO ratio). Intracellular CTLA4 expression in freshly isolated peripheral blood T-cells was significantly higher in SLE patients than the controls (P < 0.05), but there was no correlation with clinical features or disease activity. The CHO-CD80/CHO ratio of SLE patients was significantly higher than that of the controls (P < 0.05). Among SLE patients, the CHO-CD80/CHO ratio of patients with lupus nephritis was significantly higher than that of patients without lupus nephritis (P < 0.05). In conclusion, our data suggest that CTLA4 expression is not impaired in SLE patients, but there is a possibility of decreased inhibitory effect of CTLA4 involved in the pathogenesis of SLE.

A case of inclusion body myositis with systemic sclerosis.

Abstract We report a case of systemic sclerosis (SSc) associated with inclusion body myositis (IBM). A 58-year-old man was diagnosed as having SSc at the age of 35 years, and had been suffering from chronic progressive weakness and atrophy of the limb muscles. A diagnosis of IBM was established by muscle biopsy. Although most such patients show a poor response to corticosteroids and immunosupressants, glucocorticoid therapy was effective in the present case.