Central nervous system function in systemic lupus erythematosus

Autoantibodies to three eukaryotic 60S ribosomal phosphoproteins P0, P1 and P2 have been found in the sera of 10–20% of patients with systemic lupus erythematosus (SLE). These antibodies inhibit protein synthesis in vitro and when microinjected into cultured human fibroblasts. The three proteins share a common epitope contained within the carboxyl terminal 22 amino acids of each protein. Because a significant number of SLE patients have central nervous system disturbances with major behavioral disorders, the antiribosomal protein autoantibodies were measured in this subset of SLE individuals to determine whether or not there was an association. These antibodies are present in 90% of SLE patients who were diagnosed as having psychosis, secondary to the disease.Special issue dedicated to Dr. Sidney underfriend     

CTLA-4 gene polymorphisms in systemic lupus erythematosus: a highly significant association with a determinant in the promoter region

The cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4; CD 152) is a negative regulator of T-lymphocyte activation. Particular genotypes of the locus encoding the CTLA-4 glycoprotein have been associated with susceptibility to various autoimmune diseases. To determine their role in susceptibility to systemic lupus erythematosus (SLE), we genotyped 130 patients and 200 ethnically matched controls for allelic determinants at four polymorphic sites, viz., three in the promoter region at positions -1722 (T/C), -1661 (A/G), and -318 (C/T), and one within the first exon at position +49 (A/G), by restriction fragment length polymorphism methods. All genotype frequencies were in Hardy-Weinberg equilibrium. The genotypes at position -1722 were significantly associated with SLE. The frequency of T/T homozygotes was higher in patients than in controls (56% vs 33%, P=0.00003). Conversely, the frequencies of C/C homozygotes and C/T heterozygotes were higher in controls than in patients (15.5% vs 7%, P=0.019; 51.5% vs 37%, P=0.009). Genotypes at positions +49, -318, or -1661 were not significantly associated with SLE. These results show that allelic variation at the -1722 site influences susceptibility to SLE. This is the first report to our knowledge implicating CTLA-4 genotypes at the -1722 locus in susceptibility to any disease.     

NT FRZ 基因多态性与SEL 的相关性研究

本研究通过调查中国南方SLE人群和健康对照人群中TNFR2基因两个位点（nt587,nt694）的多态性频率,探讨TNFR2基因多态性是否与中国汉族SLE人群的易感性相关。结果发现128例SLE中,nt587G的等位基因频率为54个（21．1％）;而135例健康人群中nt587G的频率为35个（13．0％）;SLE组明显高于健康对照人群（P〈0．05）,携带nt587G的个体SLE发病危险性大。同时128例SLE中,舶94A的等位基因频率为41个（16．0％）;而健康人群中舶94A的频率为32个（11．9％）;两组比较无显著差异（P=0．149）。提示TNFR2基因nt587的多态性与中国南方SLE人群相关,可能通过影响TNFR2的表达而参与SLE的发病,而nt694（G—A）的多态性与中国南方SLE人群不相关。     

Screening of an endothelial cDNA library identifies the C-terminal region of Nedd5 as a novel autoantigen in systemic lupus erythematosus with psychiatric manifestations

Anti-endothelial-cell antibodies are associated with psychiatric manifestations in systemic lupus erythematosus (SLE). Our primary aim in this study was to seek and characterize molecules that behave as endothelial autoantigens in SLE patients with psychiatric manifestations. By screening a cDNA library from human umbilical artery endothelial cells with serum from an SLE patient with psychosis, we identified one positive strongly reactive clone encoding the C-terminal region (C-ter) of Nedd5, an intracytoplasmatic protein of the septin family. To evaluate anti-Nedd5 serum immunoreactivity, we analyzed by ELISA specific IgG responses in 17 patients with SLE and psychiatric manifestations (group A), 34 patients with SLE without psychiatric manifestations (group B), 20 patients with systemic sclerosis, 20 patients with infectious mononucleosis, and 35 healthy subjects. IgG specific to Nedd5 C-ter was present in 14 (27%) of the 51 SLE patients. The mean optical density value for IgG immunoreactivity to Nedd5 C-ter was significantly higher in patients of group A than in those of group B, those with infectious mononucleosis, or healthy subjects (0.17 +/- 0.14 vs, respectively, 0.11 +/- 0.07, P = 0.04; 0.11 +/- 0.06, P = 0.034; and 0.09 +/- 0.045, P = 0.003, on Student's t-test). Moreover, IgG immunoreactivity to Nedd5 C-ter was significantly higher in patients with systemic sclerosis than in patients of group B or healthy subjects (0.18 +/- 0.18 vs, respectively, 0.11 +/- 0.07, P = 0.046; and 0.09 +/- 0.045, P = 0.003). The percentage of patients with anti-Nedd5 C-ter serum IgG was higher in group A than in group B (8 (47%) of 17, vs 6 (17%) of 34, P = 0.045, on Fisher's exact test). In order to clarify a possible mechanism by which Nedd5 might be autoantigenic, we observed that Nedd5 relocated from cytoplasm to the plasma membrane of EAhy926 endothelial cells after apoptotic stimuli. In conclusion, Nedd5 is a novel autoantigen of potential clinical importance that could be successfully used for a more thorough investigation of the pathogenesis of psychiatric manifestations in SLE. Although anti-Nedd5 autoantibodies are not specific to SLE, they are significantly associated with neuropsychiatric SLE and may represent immunological markers of psychiatric manifestations in this pathology.     

Association of the diplotype configuration at the N-acetyltransferase 2 gene with adverse events with co-trimoxazole in Japanese patients with systemic lupus erythematosus

Although co-trimoxazole (trimethoprim-sulphamethoxazole) is an effective drug for prophylaxis against and treatment of Pneumocystis pneumonia, patients often experience adverse events with this combination, even at prophylactic doses. With the aim being to achieve individual optimization of co-trimoxazole therapy in patients with systemic lupus erythematosus (SLE), we investigated genetic polymorphisms in the NAT2 gene (which encodes the metabolizing enzyme of sulphamethoxazole). Of 166 patients with SLE, 54 patients who were hospitalized and who received prophylactic doses of co-trimoxazole were included in the cohort study. Adverse events occurred in 18 patients; only two experienced severe adverse events that lead to discontinuation of the drug. These two patients and three additional ones with severe adverse events (from other institutions) were added to form a cohort sample and were analyzed in a case-control study. Genotype was determined using TaqMan methods, and haplotype was inferred using the maximum-likelihood method. In the cohort study, adverse events occurred more frequently in those without the NAT2*4 haplotype (5/7 [71.4%]) than in those with at least one NAT2*4 haplotype (13/47 [27.7%]; P = 0.034; relative risk = 2.58, 95% confidence interval = 1.34-4.99). In the case-control study the proportion of patients without NAT2*4 was significantly higher among those with severe adverse events (3/5 [60%]) than those without severe adverse events (6/52 [11.5%]; P = 0.024; odds ratio = 11.5, 95% confidence interval = 1.59-73.39). We conclude that lack of NAT2*4 haplotype is associated with adverse events with co-trimoxazole in Japanese patients with SLE.     

Co-Positivity for Anti-dsDNA, -Nucleosome and -Histone Antibodies in Lupus Nephritis Is Indicative of High Serum Levels and Severe Nephropathy

ObjectiveTo characterize the significance of correlated autoantibodies in systemic lupus erythematosus (SLE) and its complication lupus nephritis (LN) in a large cohort of patients.MethodsClinical data were statistically analyzed in 1699 SLE patients with or without nephritis who were diagnosed and treated during 2002–2013 in the northeast region of China. Reactivity to a list of 16 autoantibodies was detected by the serum test Euroline ANA profile (IgG). Serum titers of the anti-nucleosome autoantibodies were measured by ELISA assays. Kidney biopsies were examined by pathologists. Immune complex deposition was identified by immunohistochemistry stain.ResultsSimultaneous positivity of anti-dsDNA, -nucleosome and -histone antibodies (3-pos) was prevalent in SLE patients with LN compared to Non-renal SLE patients (41% vs 11%, p< 0.001). Significant correlations were found between any two of the above three anti-nucleosome antibodies in LN patients. In comparison to non-3-pos cohorts, 3-pos patients with LN had significantly higher serum levels of the three antibodies and more active disease; was associated with type IV disease; suffered from more severe renal damages; received more intensive treatment and had worse disease outcome. The serum levels of these three autoantibodies in 3-pos LN patients were significantly decreased when they underwent clinical recovery.ConclusionsSimultaneous reactivity to anti-dsDNA, -nucleosome and -histone antibodies by Euroline ANA profile (IgG) may indicate severe nephropathy in patients with SLE.     

Genetic association of <Emphasis Type="Italic">IRF5</Emphasis> with SLE in Mexicans: higher frequency of the risk haplotype and its homozygozity than Europeans

The IRF5 gene was found to be strongly associated with SLE. We identified two functional polymorphisms and recently an insertion/deletion together with a tag SNP defining the risk haplotype in individuals of European ancestry. We now analyzed sets of Mexican patients with SLE. Three polymorphisms in the IRF5 gene were genotyped in two sets of Mexican individuals with SLE and controls as well as in families including a set of pediatric SLE patients. A set of healthy Mexican Indians was also typed. Genetic association with SLE was found for all three polymorphisms. The genetic association was very strong in the case–control analysis in both sets (for SNP rs2070197, combined P = 1.26 × 10⁻²¹) and in families (combined P = 0.000004). Compared to healthy individuals with European ancestry, the frequency of the risk haplotype in healthy Mexican individuals was significantly higher and even higher in the healthy Mexican Indian group. Further, a much higher frequency of the risk haplotype and of individual homozygote for it was found among Mexican SLE patients. The significantly higher frequency of homozygote individuals for the risk haplotype among Mexican SLE patients could be the result of genetic admixture, and suggests the possibility that IRF5 could be involved in the more active disease and organ involvement known to occur among Mexican SLE patients. M. V. Prasad Linga Reddy and Rafael Velázquez-Cruz contributed equally to this work.     

Semaphorin 3A is a marker for disease activity and a potential immunoregulator in systemic lupus erythematosus

Introduction

Semaphorin 3A (sema3A) and neuropilin-1 (NP-1) play a regulatory role in immune responses and have a demonstrated effect on the course of collagen induced arthritis. This study was undertaken to evaluate the role of sema3A and NP-1 in the pathogenesis of systemic lupus erythematosus (SLE) and the specific effect of sema3A on the auto-reactive properties of B cells in SLE patients.

Methods

Thirty two SLE and 24 rheumatoid arthritis (RA) patients were assessed and compared with 40 normal individuals. Sema3A serum levels were measured and correlated with SLE disease activity. The in vitro effect of sema3A in reducing Toll-like receptor 9 (TLR-9) expression in B cells of SLE patients was evaluated.

Results

Sema3A serum levels in SLE patients were found to be significantly lower than in RA patients (55.04 ± 16.30 ng/ml versus 65.54 ± 14.82 ng/ml, P = 0.018) and lower yet than in normal individuals (55.04 ± 16.30 ng/ml versus 74.41 ± 17.60 ng/ml, P < 0.0001). Altered serum sema3A levels were found to be in inverse correlation with SLE disease activity, mainly with renal damage. The expression of both sema3A and NP-1 on B cells from SLE patients was significantly different in comparison with normal healthy individuals. Finally, when sema3A was co-cultured with cytosine-phosphodiester-guanine oligodeoxynucleotides (CpG-ODN)-stimulated B cells of SLE patients, their TLR-9 expression was significantly reduced, by almost 50% (P = 0.001).

Conclusions

This is the first study in which a reduced serum level of sema3A was found in association with SLE disease activity. It also raises the possibility that sema3A may have a regulatory function in SLE.     

Gene copy-number variation and associated polymorphisms of complement component C4 in human systemic lupus erythematosus (SLE): low copy number is a risk factor for and high copy number is a protective factor against SLE susceptibility in European Americans

Interindividual gene copy-number variation (CNV) of complement component C4 and its associated polymorphisms in gene size (long and short) and protein isotypes (C4A and C4B) probably lead to different susceptibilities to autoimmune disease. We investigated the C4 gene CNV in 1,241 European Americans, including patients with systemic lupus erythematosus (SLE), their first-degree relatives, and unrelated healthy subjects, by definitive genotyping and phenotyping techniques. The gene copy number (GCN) varied from 2 to 6 for total C4, from 0 to 5 for C4A, and from 0 to 4 for C4B. Four copies of total C4, two copies of C4A, and two copies of C4B were the most common GCN counts, but each constituted only between one-half and three-quarters of the study populations. Long C4 genes were strongly correlated with C4A (R=0.695; P<.0001). Short C4 genes were correlated with C4B (R=0.437; P<.0001). In comparison with healthy subjects, patients with SLE clearly had the GCN of total C4 and C4A shifting to the lower side. The risk of SLE disease susceptibility significantly increased among subjects with only two copies of total C4 (patients 9.3%; unrelated controls 1.5%; odds ratio [OR] = 6.514; P=.00002) but decreased in those with > or =5 copies of C4 (patients 5.79%; controls 12%; OR=0.466; P=.016). Both zero copies (OR=5.267; P=.001) and one copy (OR=1.613; P=.022) of C4A were risk factors for SLE, whereas > or =3 copies of C4A appeared to be protective (OR=0.574; P=.012). Family-based association tests suggested that a specific haplotype with a single short C4B in tight linkage disequilibrium with the -308A allele of TNFA was more likely to be transmitted to patients with SLE. This work demonstrates how gene CNV and its related polymorphisms are associated with the susceptibility to a human complex disease.     

Autoantibodies against the replication protein A complex in systemic lupus erythematosus and other autoimmune diseases

Replication protein A (RPA), a heterotrimer with subunits of molecular masses 70, 32, and 14 kDa, is a single-stranded-DNA-binding factor involved in DNA replication, repair, and recombination. There have been only three reported cases of anti-RPA in systemic lupus erythematosus (SLE) and Sjögren syndrome (SjS). This study sought to clarify the clinical significance of autoantibodies against RPA. Sera from 1,119 patients enrolled during the period 2000 to 2005 were screened by immunoprecipitation (IP) of ³⁵S-labeled K562 cell extract. Antigen-capture ELISA with anti-RPA32 mAb, immunofluorescent antinuclear antibodies (ANA) and western blot analysis with purified RPA were also performed. Our results show that nine sera immunoprecipitated the RPA70–RPA32–RPA14 complex and all were strongly positive by ELISA (titers 1:62,500 to 1:312,500). No additional sera were positive by ELISA and subsequently confirmed by IP or western blotting. All sera showed fine speckled/homogeneous nuclear staining. Anti-RPA was found in 1.4% (4/276) of SLE and 2.5% (1/40) of SjS sera, but not in rheumatoid arthritis (0/35), systemic sclerosis (0/47), or polymyositis/dermatomyositis (0/43). Eight of nine patients were female and there was no racial predilection. Other positive patients had interstitial lung disease, autoimmune thyroiditis/hepatitis C virus/pernicious anemia, or an unknown diagnosis. Autoantibody specificities found in up to 40% of SLE and other diseases, such as anti-nRNP, anti-Sm, anti-Ro, and anti-La, were unusual in anti-RPA-positive sera. Only one of nine had anti-Ro, and zero of nine had anti-nRNP, anti-Sm, anti-La, or anti-ribosomal P antibodies. In summary, high titers of anti-RPA antibodies were found in nine patients (1.4% of SLE and other diseases). Other autoantibodies found in SLE were rare in this subset, suggesting that patients with anti-RPA may form a unique clinical and immunological subset.     

Identification of three new autoantibodies associated with systemic lupus erythematosus using two proteomic approaches

Our objective was to identify new serum autoantibodies associated with systemic lupus erythematosus (SLE), focusing on those found in patients with central nervous system (CNS) syndromes. Autoantigens in human brain proteins were screened by multiple proteomic analyses: two-dimensional polyacrylamide gel electrophoresis/Western blots followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis and immunoprecipitation followed by liquid chromatography-tandem mass spectrometry shotgun analysis. The presence of serum IgG autoantibodies against 11 selected recombinant antigens was assessed by Western blot and enzyme-linked immunosorbent assay (ELISA) in the sera of 106 SLE patients and 100 normal healthy controls. The O.D. values in sera from SLE patients were significantly higher than those of controls for the antigens crystallin αB (p = 0.0002), esterase D (p = 0.0002), APEX nuclease 1 (p < 0.0001), ribosomal protein P0 (p < 0.0001), and PA28γ (p = 0.0005); the first three are newly reported. The anti-esterase D antibody levels were significantly higher in the CNS group than in the non-CNS group (p = 0.016). Moreover, when the SLE patients were categorized using CNS manifestations indicating neurologic or psychiatric disorders, the anti-APEX nuclease 1 antibody levels were significantly elevated in SLE patients with psychiatric disorders (p = 0.037). In conclusion, the association of SLE with several new and previously reported autoantibodies has been demonstrated. Statistically significant associations between anti-esterase D antibodies and CNS syndromes as well as between anti-APEX nuclease 1 antibodies and psychiatric disorders in SLE were also demonstrated. The combined immunoproteomic approaches used in this study are reliable and effective methods for identifying SLE autoantigens.     

Increased level of B cell differentiation factor in systemic lupus erythematosus patients

Most autoimmune disease are driven by a dysfunction in T and B cells, but B cells are still an interesting area of research, perturbations in their development are implicated in autoimmune diseases. B cell differentiating factor (BCDF) plays a part in the differentiation of B cells. The aim was To assess the levels of BCDF, IgM and IgG in SLE patients and whether they have any peculiarity in the clinical context of SLE. Thirty six patients with SLE and 24 healthy volunteers as control were enrolled in the study. BCDF was measured using Sandwich ELISA, total human IgM and IgG were measured by calorimetric methods. The mean concentrations of BCDF and IgM were significantly higher in patients with SLE as compared with controls (P?<?0.001 and P?<?0.0001 respectively). No significant difference was observed as regard IgG. We observed positive correlation between BCDF and IgM (r?=?0.281, P?=?0.03), and between IgG and IgM, duration of the disease (r?=?0.468, P?=?0.004, r?=?0.337, P?=?0.008 respectively). Moreover we observed lower IgM level in patients with discoid lesion (P?=?0.009) and lower IgG level in those with hematologic manifestations (P?=?0.02). ROC analysis revealed area under curve (AUC) 0.861 for BCDF and 0.902 for IgM, they can delineate SLE from controls at a cut-off value of 98.5?pg/ml, and 18?mg/dl IgM respectively.

系统性红斑狼疮外周血单个核细胞cFLIP—L mRNA和cFLIP—S mRNA表达的研究

目的探讨系统性红斑狼疮（system lupus erythematosus,SLE）患者外周血单个核细胞（peripheral blood monouuclear cells,PBMC）中细胞型Fas相关死亡域样白介素-1β转换酶抑制蛋白（cFLIP）表达的意义。方法应用半定量RT—PCR方法检测38例SLE患者和21名正常人PBMC中cFLIP—L mRNA和cFLIP—S mRNA的表达水平,并与SLE疾病活动指数（SLEDAI）评分进行相关性分析。结果①SLE患者PBMC中cFLIP—L mRNA和cFLIP—S mRNA表达水平均明显高于正常对照组（P〈0．01）;SLE患者活动组cFLIP—L mRNA表达水平显著高于非活动组（P〈0．05）,cFLIP—S mRNA表达水平在SLE患者活动组与非活动组之间没有显著性差异（P〉0．05）。②SLE患者cFLIP—L mRNA表达水平与SLEDAI评分呈正相关（r=0．423,P〈0．01）;而eFLIP—S mRNA表达水平与SLEDAI评分无明显相关性（r=0．270,P〉0．05）。结论cFLIP—L mRNA和cFLIP—S mRNA可能在SLE发病机制中起重要作用。     

Circulating total and active metalloproteinase-9 and tissue inhibitor of metalloproteinases-1 in patients with systemic lupus erythomatosus

We investigated the serum concentration of total metalloproteinase-9 (tMPP-9), active MMP-9 (aMMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in a group of 41 patients with SLE and 20 healthy controls. Serum levels of tMMP-9 and TIMP-1 were assessed by an enzyme-linked immunosorbent assay (ELISA) and aMMP-9 by fluorometric assay. The tMMP-9 level was lower in SLE patients (mean 262 ng/mL) than in healthy volunteers (mean 325 ng/mL) (P = .048). Similarly, aMMP-9 level was lower in SLE patients (mean 121 ng/mL) than in control group (mean 169 ng/mL) (P = .0355) and lower in active SLE (mean 54 ng/mL) than in inactive disease (mean 99 ng/mL) (P = .033). TIMP-1 level was also lower in SLE patients (mean 181 ng/mL) than in control group (mean 233 ng/mL) (P = .004). In SLE patients, a positive correlation was found between tMMP-9 and aMMP-9 (rho = 0.568; P = .001). We also found a positive correlation of tMMP-9 and TIMP-1 with VEGF concentrations (rho = 0.450, P = .005 and rho = 0.387; P = .018, resp). tMMP-9, aMMP-9, and TIMP-1 serum levels are lower in SLE patients than in healthy control group.     

Patients with systemic lupus erythematosus have abnormally elevated Epstein-Barr virus load in blood

Various genetic and environmental factors appear to be involved in systemic lupus erythematosus (SLE). Epstein-Barr virus (EBV) is among the environmental factors that are suspected of predisposing to SLE, based on the characteristics of EBV itself and on sequence homologies between autoantigens and EBV antigens. In addition, higher titers of anti-EBV antibodies and increased EBV seroconversion rates have been observed in SLE patients as compared with healthy control individuals. Serologic responses do not directly reflect EBV status within the body. Clarification of the precise status of EBV infection in SLE patients would help to improve our understanding of the role played by EBV in this disease. In the present study we determined EBV types in SLE patients (n = 66) and normal control individual (n = 63) by direct PCR analysis of mouthwash samples. We also compared EBV load in blood between SLE patients (n = 24) and healthy control individuals (n = 29) using semiquantitative PCR assay. The number of infections and EBV type distribution were similar between adult SLE patients and healthy control individuals (98.5% versus 94%). Interestingly, the EBV burden in peripheral blood mononuclear cells (PBMCs) was over 15-fold greater in SLE patients than in healthy control individuals (mean +/- standard deviation: 463 +/- 570 EBV genome copies/3 microg PBMC DNA versus 30 +/- 29 EBV genome copies/3 microg PBMC DNA; P = 0.001), suggesting that EBV infection is abnormally regulated in SLE. The abnormally increased proportion of EBV-infected B cells in the SLE patients may contribute to enhanced autoantibody production in this disease.     

Deficiency of functional mannose-binding lectin is not associated with infections in patients with systemic lupus erythematosus

Infection imposes a serious burden on patients with systemic lupus erythematosus (SLE). The increased infection rate in SLE patients has been attributed in part to defects of immune defence. Recently, the lectin pathway of complement activation has also been suggested to play a role in the occurrence of infections in SLE. In previous studies, SLE patients homozygous for mannose-binding lectin (MBL) variant alleles were at an increased risk of acquiring serious infections in comparison with patients who were heterozygous or homozygous for the normal allele. This association suggests a correlation between functional MBL level and occurrence of infections in SLE patients. We therefore investigated the biological activity of MBL and its relationship with the occurrence of infections in patients with SLE. Demographic and clinical data were collected in 103 patients with SLE. Functional MBL serum levels and MBL-induced C4 deposition were measured by enzyme-linked immunosorbent assay using mannan as coat and an MBL- or C4b-specific monoclonal antibody. The complete MBL-dependent pathway activity was determined by using an assay that measures the complete MBL pathway activity in serum, starting with binding of MBL to mannan, and was detected with a specific monoclonal antibody against C5b-9. Charts were systematically reviewed to obtain information on documented infections since diagnosis of SLE. Major infections were defined as infections requiring hospital admission and intravenous administration of antibiotics. In total, 115 infections since diagnosis of lupus, including 42 major infections, were documented in the 103 SLE patients (mean age 41 ± 13 years, mean disease duration 7 ± 4 years). The percentage of SLE patients with severe MBL deficiency was similar to that in 100 healthy controls: 13% versus 14%, respectively. Although deposition of C4 to mannan and MBL pathway activity were reduced in 21% and 43% of 103 SLE patients, respectively, neither functional MBL serum levels nor MBL pathway activity was associated with infections or major infections in regression analyses. In conclusion, SLE patients frequently suffer from infections, but deficiency of functional MBL does not confer additional risk.     

Deficiency of functional mannose-binding lectin is not associated with infections in patients with systemic lupus erythematosus

Infection imposes a serious burden on patients with systemic lupus erythematosus (SLE). The increased infection rate in SLE patients has been attributed in part to defects of immune defence. Recently, the lectin pathway of complement activation has also been suggested to play a role in the occurrence of infections in SLE. In previous studies, SLE patients homozygous for mannose-binding lectin (MBL) variant alleles were at an increased risk of acquiring serious infections in comparison with patients who were heterozygous or homozygous for the normal allele. This association suggests a correlation between functional MBL level and occurrence of infections in SLE patients. We therefore investigated the biological activity of MBL and its relationship with the occurrence of infections in patients with SLE. Demographic and clinical data were collected in 103 patients with SLE. Functional MBL serum levels and MBL-induced C4 deposition were measured by enzyme-linked immunosorbent assay using mannan as coat and an MBL- or C4b-specific monoclonal antibody. The complete MBL-dependent pathway activity was determined by using an assay that measures the complete MBL pathway activity in serum, starting with binding of MBL to mannan, and was detected with a specific monoclonal antibody against C5b-9. Charts were systematically reviewed to obtain information on documented infections since diagnosis of SLE. Major infections were defined as infections requiring hospital admission and intravenous administration of antibiotics. In total, 115 infections since diagnosis of lupus, including 42 major infections, were documented in the 103 SLE patients (mean age 41 +/- 13 years, mean disease duration 7 +/- 4 years). The percentage of SLE patients with severe MBL deficiency was similar to that in 100 healthy controls: 13% versus 14%, respectively. Although deposition of C4 to mannan and MBL pathway activity were reduced in 21% and 43% of 103 SLE patients, respectively, neither functional MBL serum levels nor MBL pathway activity was associated with infections or major infections in regression analyses. In conclusion, SLE patients frequently suffer from infections, but deficiency of functional MBL does not confer additional risk.     

Mannose binding lectin: a biomarker of systemic lupus erythematosus disease activity

Introduction

A role for mannose binding lectin (MBL) in autoimmune diseases has been demonstrated earlier and elevated level of MBL has been shown in systemic lupus erythematosus (SLE) patients. In the current study, we investigated MBL as a potential biomarker for disease activity in SLE.

Methods

In a case control study SLE patients (93 females) and 67 age, sex, ethnicity matched healthy controls were enrolled. Plasma MBL levels were quantified by enzyme linked immunosorbent assay (ELISA). Clinical, serological and other markers of disease activity (C3, C4 and anti-dsDNA) were measured by standard laboratory procedures.

Results

Plasma MBL levels were significantly high in SLE patients compared to healthy controls (P < 0.0001). MBL levels were variable in different clinical categories of SLE. Lower levels were associated with musculoskeletal and cutaneous manifestations (P = 0.002), while higher and intermediate MBL levels were significantly associated with nephritis in combination with other systemic manifestations (P = 0.01 and P = 0.04 respectively). Plasma MBL correlated with systemic lupus erythematosus disease activity index (SLEDAI) (P = 0.0003, r = 0.36), anti-dsDNA (P < 0.0001, r = 0.54), proteinuria (P < 0.0001, r = 0.42) and negatively correlated with C3 (P = 0.007, r = -0.27) and C4 (P = 0.01, r = -0.29).

Conclusions

Plasma MBL is a promising marker in the assessment of SLE disease activity.     

C4A gene deletion and HLA associations in black Americans with systemic lupus erythematosus

In North America and European Caucasoids with systemic lupus erythematosus (SLE) there is an increased frequency of aC4A, CYP21A gene deletion, largely associated with theHLA-B8,DR3,C4A ^* QO extended haplotype. There have been no consistent HLA associations reported for SLE in blacks, although an increased frequency of serologically determinedC4A null alleles has been reported in two studies. We studied 79 black American SLE patients and 68 black controls by restriction fragment length polymorphism analysis to dermine if aC4A gene deletion was a genetic risk factor for SLE. Moreover, the nature of the deletion and any HLA phenotypic associations were sought. Nineteen of 79 (24%) patients compared to 5 of 68 (7.4%) controls had a phenotypicC4A,CYP21A gene deletion (P=.005; RR=4). A homozygous deletion in four patients gave a genotypic frequency of 23/158 (14.5%) SLE patients vs 5/136 (3.7%) controls (P=.001; RR=4.5). The deletion was associated with HLA-DR2 (P=.03) and HLA-DR3 (P=.03). Moreover, all subjects with the deletion had HLA-DR2 or DR3 (P=7.7×10⁻⁶). HLA-B44 was also associated with the deletion (P=.02), and eight of the nine HLA-B44 positives also carried HLA-DR2. HLA-B8 approached significance (P=.08) and was always accompanied by HLA-DR3. Finally, this black population demonstrated a uniqueC4B gene size polymorphism with 80% C4B “short” as compared to the 40% C4B “short” frequency reported in whites. We conclude that a largeC4A,CYP21A gene deletion, particularly associated with theHLA-B44,-DR2, and-DR3 alleles, is the strongest genetic risk factor thus far identified for SLE susceptibility in black Americans. Furthermore, the unique preponderance of theC4B “short” gene form may be a factor in the actual formation of the deletion.     

系统性红斑狼疮患者血清MBL水平变化及其临床意义

目的：研究系统性红斑狼疮（SLE）患者外周血中甘露糖结合凝集素（MBL）水平与SLE的临床表现、经典的血清学指标及疾病活动性指数的相关性。方法：应用固相酶联免疫吸附（ELISA）法检测54例（其中活动期39例、缓解期15例）SLE患者和45名健康志愿者外周血MBL水平,同时检测SLE患者外周血抗dsDNA抗体、C3补体、白细胞计数及循环免疫复合物（CICs）水平,并记录SLE患者主要临床症状（肾脏系统受累、神经系统受累、严重感染等）,疾病活动度用SLEDAI记分。结果：系统性红斑狼疮患者外周血MBL水平显著低于健康志愿者（P〈0．01）;特别是活动期SLE患者血清MBL水平明显降低,与缓解组比较差别具有统计学意义（P〈0．01）;SLE患者血清MBL水平与SLEDAI、抗dsDNA抗体、CICs水平呈负相关,与白细胞计数及C3补体水平呈正相关;并发严重感染的SLE患者组血清MBL水平显著低于无受累组（P〈0．01）。结论：SLE患者血清MBL水平明显降低,血清MBL水平与SLEDAI、抗dsDNA抗体、C3水平、CIC水平、白细胞水平之间明显相关,血清MBL水平较低的患者更易发生比较严重的感染,血清MBL水平可能是SLE潜在生物学标记。