Epstein–Barr virus antibodies mark systemic lupus erythematosus and scleroderma patients negative for anti‐DNA

Systemic lupus erythematosus (SLE) is an autoimmune disease that can attack many different body organs; the triggering event is unknown. SLE has been associated with more than 100 different autoantibody reactivities – anti‐dsDNA is prominent. Nevertheless, autoantibodies to dsDNA occur in only two‐thirds of SLE patients. We previously reported the use of an antigen microarray to characterize SLE serology. We now report the results of an expanded study of serology in SLE patients and scleroderma (SSc) patients compared with healthy controls. The analysis validated and extended previous findings: two‐thirds of SLE patients reacted to a large spectrum of self‐molecules that overlapped with their reactivity to dsDNA; moreover, some SLE patients manifested a deficiency of natural IgM autoantibodies. Most significant was the finding that many SLE patients who were negative for autoantibodies to dsDNA manifested abnormal antibody responses to Epstein–Barr virus (EBV): these subjects made IgG antibodies to EBV antigens to which healthy subjects did not respond or they failed to make antibodies to EBV antigens to which healthy subjects did respond. This observation suggests that SLE may be associated with a defective immune response to EBV. The SSc patients shared many of these serological abnormalities with SLE patients, but differed from them in increased IgG autoantibodies to topoisomerase and centromere B; 84% of SLE patients and 58% of SSc patients could be detected by their abnormal antibodies to EBV. Hence an aberrant immune response to a ubiquitous viral infection such as EBV might set the stage for an autoimmune disease.     

Prevalence of autoimmune diseases and clinical significance of autoantibody profile: Data from National Institute of Hygiene in Rabat,Morocco

AimThe objective of this study was to explore the prevalence of various autoimmune diseases (AIDs) in a large cohort of patients and to characterize the autoantibody profile in the patients with and without AIDs to confirm the diagnosis and to refine the Moroccan databases.Patients and methodRetrospective study was conducted in the Laboratory of autoimmunity National Institute of Hygiene (NIH) of Rabat in Morocco. A total of 3182 consecutive Moroccan patients (2183 females and 999 males) whose sera were tested for 14 autoantibody profile between 2010 and 2016.ResultsOnly 944 (29.7%) patients were diagnosed with AIDs of those suspected. The prevalence of systemic lupus erythematosus (SLE), intestinal malabsorption (IM) and arthritis polyarthralgia (AP) were the highest (4.2, 4.1 and 4%), subsequently followed by rheumatoid arthritis (RA) (2.8%), cholestatic syndrome (CS) (1.8%), interstitial lung disease (ILD) (1.6%).In females IM, AP and SLE also showed the highest prevalence (5.4%, 5.3% and 4.9% respectively), while of male, SLE showed the highest prevalence (1.9%). The prevalence of ANA was increased in most patients with systemic especially in neuropathy (NP), hemolytic anemia (HA), primary Sjogren’s syndrome (pSS), dermatomyositis (DM), thrombocytopenia (Tb), systemic sclerosis (SSc), ANCA-associated vasculitis (AAV), AP, Renal impairment (RI), SLE, and mixed connective tissue disease (MCTD). Anti-dsDNA antibodies were higher in SLE and ENA showed the highest titers in MCTD. Others are relatively specific for certain disease, such as anti β2GP1 for thrombosis syndrome, anti ANCA for primary sclerosing cholangitis (PSC), AAV, ILD and RI, anti CCP2 for RA, ILD and AP. the prevalence of anti AMA was higher in primary biliary cirrhosis (PBC), followed in CS, also, ANA have been identified in up to 25% of patients with primary biliary cirrhosis. The prevalence of anti-SMA was higher in PBC, treated patients for Chronic hepatitis C (HCV), and autoimmune hepatitis (AIH) and anti-PCA was higher in biermer anemia patients with vitamin B12 deficiency (BA/Def vit B12). The prevalence of IgA EMA, IgA tTG and IgA AGA were higher in patients IM and celiac disease (CD). The prevalence of anti thyroperoxidase (TPO) was significantly increased in the autoimmune thyroiditis (AIT).ConclusionOur study shows the diagnostic value of auto antibodies in AIDs. It would be interesting to carry out prospective studies on each pathology separately, in order to fill the classic vagaries of the retrospective study and objectively estimate the prevalence in different AIDs. These data on the prevalence of each autoimmune disease are valuable for the public health system.     

The prevalence of autoantibody and its relationship with genotypes of hepatitis C virus in patients with chronic hepatitis C virus infection

The prevalence of autoantibody in the patients with chronic hepatitis C infection, and the relationship between the autoantibodies and HCV genotypes were investigated in this study. One hundred and eight anti‐HCV positive and 86 anti‐HCV negative patients were included in the study. Anti‐HCV were studied by enzyme immunassay (EIA). HCV RNA was determined by real time polymerase chain reaction (PCR) and HCV genotypes were determined by a reverse‐line blot hybridization. Anti‐nuclear antibodies (ANA), anti‐smooth muscle antibodies (ASMA), Anti‐mitochondrial antibodies (AMA), liver kidney microsomal antibodies (LKM) were detected by indirect immunofluorescence assay. Among patients, 13 (12.03%) of 108 were positive for at least one autoantibody. The positivity was not observed in control group. The most prevalent autoantibody in anti‐HCV positive group was ANA. ANA was positive in six HCV patients with genotype 1. In HCV patients with genotype 1, the frequencies of ANA, ASMA, AMA and LKM1 were six, two, three and one, respectively. In HCV patients with genotype 2, ANA was positive one patient and ASMA, AMA and LKM1 were not detected in HCV patients with genotype 2. In conclusion, the autoantibodies in patients with chronic hepatitis C in the study were low as compared to those reported in previous studies.     

Comparisons of neutrophil‐, monocyte‐, eosinophil‐, and basophil‐ lymphocyte ratios among various systemic autoimmune rheumatic diseases

This study was aimed to evaluate levels of neutrophil‐ (NLR), monocyte‐ (MLR), eosinophil‐ (ELR), and basophil‐lymphocyte ratio (BLR) and their association with inflammatory markers in systemic autoimmune rheumatic diseases (SARDs). A total of 1139 SARD patients and 170 healthy individuals were enrolled. Clinical and laboratory data were extracted. NLR and MLR were significantly increased, but BLR decreased in most SARD patients (p < 0.05). ELR were significantly decreased in systemic lupus erythematosus (SLE) patients, but increased in those with other SARDs (p < 0.001). In SLE patients, C‐reactive protein (CRP) showed positive correlation with NLR, MLR, and BLR. IgG negatively correlated with NLR, and did positively with ELR. IgM negatively correlated with NLR and MLR. In those with rheumatoid arthritis (RA), ankylosing spondylitis (AS), and osteoarthritis (OA), NLR and MLR positively correlated with erythrocyte sedimentation rate (ESR) and CRP. In primary Sjögren's syndrome (pSS) patients, ESR showed positive correlation with NLR and MLR. IgA had positive correlation with BLR. In polymyositis/dermatomyositis (PM/DM) patients, ESR and CRP positively correlated with NLR. Additionally, significant correlations were also found between CRP and BLR, IgG and ELR, IgM and ELR. In systemic sclerosis (SSc) patients, clear correlations were only observed between CRP and NLR or MLR. In mixed connective tissue disease (MCTD) patients, NLR positively correlated with ESR and CRP, while NLR and MLR did negatively with IgM. In polymyalgia rheumatic (PMR) patients, MLR positively correlated with CRP, while ELR did negatively with IgG. This study demonstrated increased NLR and MLR and deceased BLR in most SARDs, decreased ELR in SLE and increased ELR in other SARDs. Furthermore, NLR and MLR may be useful tools to reflect inflammatory status of SARDs.     

Distribution and antigen specificity of anti-U1RNP antibodies in patients with systemic sclerosis.

Systemic sclerosis (SSc) is a generalized connective tissue disease which is characterized by the presence of several autoantibodies. To determine the prevalence and antigen specificity of anti-U1RNP antibodies (anti-U1RNP) in patients with SSc, serum samples from 223 patients with SSc, 117 patients with systemic lupus erythematosus (SLE), 18 patients with mixed connective tissue disease (MCTD) and 40 healthy control subjects were examined by indirect immunofluorescent analysis (IIF), double immunodiffusion, and immunoblotting using nuclear extract of HeLa cells. Eighteen of the 223 (8%) serum samples from patients with SSc were shown to be positive for anti-U1RNP. The frequency of anti-U1RNP positivity in limited cutaneous SSc (14%) was significantly higher than that in those with diffuse cutaneous SSc (3%). Anti-Sm antibodies were detected in patients with SLE positive for anti-U1RNP, but not in those with SSc positive for anti-U1RNP or those with MCTD. Immunoblotting demonstrated that anti-70-kD antibodies were detected more often in patients with SSc positive for anti-U1RNP and in those with MCTD than in those with SLE. Furthermore, anti-U1RNP was closely correlated with pulmonary fibrosis and joint involvement in patients with SSc. These results suggest that anti-70-kD antibodies are useful in the classification of patients with anti-U1RNP.     

Evaluation of anti-nuclear antibodies and kidney pathology in Lewis rats following exposure to Libby amphibole asbestos

Abstract

The prevalence of anti-nuclear antibodies (ANA) and self-reported systemic autoimmune diseases were increased in residents of Libby, MT, as was the incidence of ANA in Lewis rats exposed to Libby amphibole (LA) asbestos. However, rats induced to develop rheumatoid arthritis (RA) did not develop autoantibodies associated with RA, nor was RA exacerbated by LA exposure, suggesting that increased ANA expression might be related to some other autoimmune process. Libby residents self-reported increased numbers of physician-diagnosed cases of systemic lupus erythematosus (SLE). Thus, the goal of this study was to determine if the increased incidence of ANA in Lewis rats exposed to LA is related to the development of SLE-like disease. Female Lewis rats were intratracheally instilled bi-weekly for 13 weeks with total doses of 0.15, 0.5, 1.5, or 5.0?mg of LA or 0.5 or 1.5?mg of a positive control fiber, amosite. ANA incidence was significantly increased in all asbestos dose groups, although no dose response was observed. The occurrence of proteinuria was increased in LA 0.5, LA 5.0, and amosite 0.5 dose groups; however, the microscopic appearance of the kidneys was normal, no binding of autoimmune complexes to glomerular surfaces was observed, and antibodies to double-stranded DNA were not elevated. Therefore, an increased prevalence of ANA in rats exposed to asbestos does not appear to correlate with disease markers typically observed in SLE. Analysis of ANA specificity for extractable nuclear antigens (ENA) determined that 98% of ENA⁺ samples were specific for the Jo-1 antigen. Autoantibodies to Jo-1 have been reported in patients with interstitial lung disease, suggesting that autoantibodies to Jo-1 may be a biomarker for asbestos-related pulmonary disease.     

Antinuclear antibody detection by automated multiplex immunoassay in untreated patients at the time of diagnosis

Fully automated multiplex immunoassays are increasingly used as first line screening for antinuclear antibodies. The diagnostic performance of such multiplex assays in untreated patients at the time of diagnosis has not been reported.Antinuclear antibodies were measured by indirect immunofluorescence (IIF) (dilution 1:160) and by BioPlex 2200 ANA screen (antibodies to dsDNA, chromatin, ribosomal protein, SSA-52, SSA-60, SSB, Sm, SmRNP, RNP-A, RNP-68, Scl-70, Jo-1, and centromere B) in 236 patients with a systemic rheumatic disease at the time of diagnosis, 149 blood donors, 139 patients with chronic fatigue syndrome (CFS), and 134 diseased controls.BioPlex ANA screen and IIF were positive in, respectively, 79% and 90% of patients with systemic lupus erythematosus (SLE), 60% and 60% with cutaneous lupus, 72% and 93% with systemic sclerosis (SSc), 100% and 100% with mixed connective tissue disease (MCTD), 89% and 56% with primary Sjögren's (SS) syndrome, 36% and 36% with polymyositis/dermatomyositis, 5.4% and 6% of blood donors, 7.2% and 3.6% of patients with CFS, and 11% and 18% of diseased controls. BioPlex test result interval specific likelihood ratios increased with increasing antibody concentration. The simultaneous presence of at least three antibodies by BioPlex was found in 35% of patients with SLE, 4% with SSc, 100% with MCTD, 64% with SS, 7% with inflammatory myopathy, 0.7% of CFS and diseased controls, and none of the blood donors.In conclusion, test result specific likelihood ratios and the presence of multiple autoantibodies help with the interpretation of data generated by multiplex immunoassays.     

Modelling autoimmune rheumatic disease: a likelihood rationale

Immunoglobulins (Igs) and autoantibodies are commonly tested in sera from patients with suspected rheumatic disease. To evaluate the clinical utility of the tests in combination, we investigated sera from 351 patients with autoimmune rheumatic disease (ARD) rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS) and 96 patients with nonautoimmune rheumatic disease (NAD) (fibromyalgia, osteoarthritis, etc.). Antinuclear antibodies (ANA), rheumatoid factor (RF), antibodies against DNA and extractable nuclear antigens (anti‐ENA), IgG, IgA and IgM were measured for all patients. Logistic regression analysis of test results was used to calculate each patient's probability for belonging to the ARD or NAD group as well as likelihood ratios for disease. Test accuracy was investigated using receiver‐operating characteristic (ROC) plots and nonparametric ROC analysis. Neither concentrations of IgG, IgA, IgM, anti‐DNA nor anti‐ENA gave a significant effect on diagnostic outcome. Probabilities for disease and likelihood ratios calculated by combining RF and ANA performed significantly better at predicting ARD than utilization of the diagnostic tests in isolation (P < 0.001). At a cut‐off level of P = 0.73 and likelihood ratio = 1, the logistic model gave a specificity of 93% and a sensitivity of 75% for the differentiation between ARD and NAD. When compared at the same level of specificity, ANA gave a sensitivity of 37% and RF gave a sensitivity of 56.6%. Dichotomizing ANA and RF as positive or negative did not reduce the performance characteristics of the model. Combining results obtained from serological analysis of ANA and RF according to this model will increase the diagnostic utility of the tests in rheumatological practice.     

Associations of B cell‐activating factor (BAFF) and anti‐BAFF autoantibodies with disease activity in multi‐ethnic Asian systemic lupus erythematosus patients in Singapore

To measure the levels of B cell‐activating factor (BAFF) and endogenous anti‐BAFF autoantibodies in a cohort of multi‐ethnic Asian systemic lupus erythematosus (SLE) patients in Singapore, to determine their correlation with disease activity. Serum samples from 121 SLE patients and 24 age‐ and sex‐matched healthy controls were assayed for BAFF and anti‐BAFF immunoglobulin (Ig)G antibody levels by enzyme‐linked immunosorbent assay (ELISA). The lowest reliable detection limit for anti‐BAFF‐IgG antibody levels was defined as 2 standard deviations (s.d.) from blank. Correlation of serum BAFF and anti‐BAFF IgG levels with disease activity [scored by SLE Activity Measure revised (SLAM‐R)], and disease manifestations were determined in these 121 patients. SLE patients had elevated BAFF levels compared to controls; mean 820 ± 40 pg/ml and 152 pg ± 45/ml, respectively [mean ± standard error of the mean (s.e.m.), P < 0·01], which were correlated positively with anti‐dsDNA antibody levels (r = 0·253, P < 0·03), and SLAM‐R scores (r = 0·627, P < 0·01). In addition, SLE patients had significantly higher levels of anti‐BAFF IgG, which were correlated negatively with disease activity (r = –0·436, P < 0·01), levels of anti‐dsDNA antibody (r = –0·347, P < 0·02) and BAFF (r = –0·459, P < 0·01). The majority of patients in this multi‐ethnic Asian SLE cohort had elevated levels of BAFF and anti‐BAFF antibodies. Anti‐BAFF autoantibody levels correlated negatively with clinical disease activity, anti‐dsDNA and BAFF levels, suggesting that they may be disease‐modifying. Our results provide further information about the complexity of BAFF pathophysiology in different SLE disease populations and phenotypes, and suggest that studies of the influence of anti‐cytokine antibodies in different SLE populations will be required when selecting patients for trials using targeted anti‐cytokine therapies.     

Clinical relevance of circulating anti‐ENA and anti‐dsDNA secreting cells from SLE patients and their dependence on STAT‐3 activation

Disturbances of plasma cell homeostasis and auto‐antibody production are hallmarks of systemic lupus erythematosus. The aim of this study was to explore the presence of circulating anti‐ENA and anti‐dsDNA antibody‐secreting cells, to determine their dependence on plasma cell‐niche cytokines and to analyze their clinical value. The study was performed in SLE patients with serum anti‐ENA and/or anti‐dsDNA antibodies (n = 57). Enriched B‐cell fractions and sorted antibody‐secreting cells (CD19^lowCD38^high) were obtained from blood. dsDNA‐ and ENA‐specific antibody‐secreting cells were identified as cells capable of active auto‐antibody production in culture. The addition of a combination of IL‐6, IL‐21, BAFF, APRIL, and CXCL12 to the cultures significantly augmented auto‐antibody production and antibody‐secreting cell proliferation, whereas it diminished apoptosis. The effect on auto‐antibody production was dependent on STAT‐3 activation as it was abrogated in the presence of the JAK/STAT‐3 pathway inhibitors ruxolitinib and stattic. Among patients with serum anti‐dsDNA antibodies, the detection of circulating anti‐dsDNA‐antibody‐secreting cells was associated with higher disease activity markers. In conclusion, auto‐antibody production in response to plasma cell‐niche cytokines that are usually at high levels in SLE patients is dependent on JAK/STAT‐3 activation. Thus, patients with circulating anti‐dsDNA antibody‐secreting cells and active disease could potentially benefit from therapies targeting the JAK/STAT3 pathway.     

Prevalence and clinical characteristics of the dense fine speckled pattern: Indirect immunofluorescence-antinuclear antibody screening in the Chinese population

To investigate the prevalence and clinical significance of the dense fine speckled (DFS) pattern in a large-scale cohort of Chinese patients. Data on the antinuclear antibody (ANA) and extractable nuclear antigen (ENA) autoantibody obtained from 165 498 patients who attended Peking Union Medical College Hospital from January 2019 to December 2021 were retrospectively analysed. The prevalence of the DFS pattern was 1.14%, and it mainly appeared in young patients (≤24 years old). A higher positive rate of the DFS pattern was observed in patients with dermatosis (18.12%) and systemic autoimmune rheumatic diseases (SARDs) (13.53%). The DFS pattern titre was mostly low or medium (≤1:160). A higher titre was associated with an increased risk of SARDs (p < .001), dermatosis (p = .015) and pulmonary disease (p = .016). In 37 patients with ENA autoantibody positivity, anti-SSA antibody was the most common (2.55%). If the low titre (<1:160) or the DFS pattern with negative ENA autoantibody were to be used as exclusion criteria for SARDs, the diagnosis would have been missed in 42 or 77 patients, respectively. The prevalence of the DFS pattern was low in ANA test samples and was more common in patients with dermatosis and SARDs, but the titre was usually higher in patients with SARDs. There was no evidence that the DFS pattern could be used as an exclusion criterion for SARDs diagnosis. The DFS pattern was associated with certain pathological states, which may inform the clinical significance of the DFS pattern.     

The effect of interleukin-10 and of interleukin-12 on the in vitro production of anti-double-stranded DNA antibodies from patients with systemic lupus erythematosus

IL-10 and IL-12 are cytokines which are important in regulating immune responses. Plasma levels of IL-10 and autoantibodies against double-stranded DNA (dsDNA) often mirror disease activity in patients with SLE. IL-12 secretion from SLE patients' blood mononuclear cells also correlates with disease activity, but has an inverse relationship. The aim of this study was to measure the effect of IL-10 and of IL-12 on the production of IgG autoantibodies from patients with SLE, both cross-sectionally and longitudinally. Peripheral blood mononuclear cells (PBMC) were cultured with IL-10 (at 20 ng/ml or 2 ng/ml) or IL-12 (at 2 ng/ml or 0.2 ng/ml) or without cytokine and the supernatanants tested for the production of double-stranded DNA antibodies (dsDNA abs), single-stranded DNA antibodies (ssDNA abs) and total IgG antibodies (IgG abs) by ELISA. The BILAG disease activity index was recorded at each patient visit (a global score of six or more is regarded as active disease). In general, treatment with IL-10 caused PBMCs from patients with inactive disease to increase their antissDNA and dsDNA ab production (by upto 354% and 186%, respectively) while patients with active disease decreased their antibody production (by upto 91% and 97%, respectively). Overall there was a correlation between disease activity and change in antissDNA and dsDNA ab production (r = - 0.51; P = 0.03 and r = - 0.48; P = 0.042, respectively). Treatment with IL-12 at 0.2 ng/ml inhibited antissDNA and dsDNA antibody production, having the greatest effect on patients with active disease (decreasing antissDNA and dsDNA antibody production by upto 75% and 73%, respectively). This resulted in a significant correlation between disease activity and change in antissDNA antibody production (r = - 0.76; P = 0.03), but significance was not reached with antidsDNA antibody production (P = 0.06). Together these data suggest that the effect of these cytokines on antibody production by SLE PBMCs involves several factors; one of which is disease activity.     

核不均一性胞核核糖核蛋白Ⅰ(hnRNPI)抗原表位在系统性硬化症中临床意义的研究

目的探讨核不均一性胞核核糖核蛋白I(hnRNPI)抗原表位多肽在系统性硬化症(systemic sclerosis,SSc)中的临床意义,初步建立简便快捷的ELISA检测方法,为系统性硬化症的早期诊断寻找新的临床指标。方法根据已知的hnRNPI蛋白的氨基酸序列,应用不同的蛋白质抗原表位图谱分析软件对其进行表位分析,经比对筛选后,化学合成hnRNPI短肽序列2个,分别命名为I-1_(264-292)及I-2_(441-461),作为抗原对临床上包括硬皮病在内的多种结缔组织病患者血清相应抗体进行ELISA检测,包括SSc 42例、系统性红斑狼疮(SLE)102例、干燥综合征(SS)26例、混合型结缔组织病(MCTD)16例、未分化结缔组织病(UCTD)13例,其他结缔组织病(CTD)30例、类风湿关节炎(RA)26例及正常对照54例。结果抗hnRNPI-1及抗hnRNPI-2多肽抗体在SSc组中阳性率均明显高于其他疾病组(P<0.05),在SSc中敏感性分别为47.62%及38.1%,特异性分别为93.43%及91.08%,二者之间差异无统计学意义(P>0.05)。另外,除了与SSc患者病程相关外,该二抗体均与发病年龄、临床症状、器官受累、ESR、抗Scl-70抗体、抗着丝点抗体及抗核仁抗体之间未发现有统计学意义的相关性(P>0.05)。结论I-1及I-2分别是位于hnRNPI蛋白表面的抗原表位之一,具有抗原性,其抗体对SSc的临床诊断具有较高的敏感性及特异性,且在病程早期具有更高的阳性率,有助于SSc的早期诊断。     

A cross-sectional hospital-based study of autoantibody profile and clinical manifestations of systemic lupus erythematosus in south Indian patients

Our study was aimed to analyze clinical manifestations, autoantibodies and other serological abnormalities in South Indian patients with systemic lupus erythematosus. Clinical history and findings on systemic examination were noted. Antinuclear antibodies (ANA), antibodies to double-stranded DNA (dsDNA) were detected by immunofluorescence and ANA profile by Immunoblotting. Arthritis was most common followed by fever and skin rash. Clinical manifestations vary according to geographical location of the patient. ANA was positive in 64.28% and anti-dsDNA in 89.36% of patients. All patients with lupus nephritis were positive for dsDNA. Detection of antibodies to dsDNA, RNP and anti-Smith (Sm) are of diagnostic and prognostic importance.     

Clinical significance of autoantibodies recognizing Sjögren's syndrome A (SSA), SSB, calpastatin and alpha-fodrin in primary Sjögren's syndrome

The aim of our study was (i) to compare the clinical and biological characteristics of 148 (137 women, 11 men) primary Sjögren's syndrome (pSS) patients at diagnosis as a function of their sex and (ii) to assess the prognostic value of anti‐calpastatin and anti‐alpha‐fodrin autoantibodies. In addition, the presence of anti‐nuclear antibodies (ANA), anti‐52‐ and 60‐kDa Sjögren's syndrome A (SSA), anti‐Sjögren's syndrome B (SSB), anti‐cyclic citrullinated peptide (CCP) antibodies and rheumatoid factors (RF) of IgA, IgG and IgM isotypes was sought in sera collected at pSS onset. Raynaud's syndrome, significantly more frequent in women, was the only systemic manifestation of pSS whose frequency differed significantly as a function of the patient's sex (P = 0·02). ANA (P = 0·001) and anti‐60‐kDa SSA autoantibodies (P = 0·03) were significantly more common in women, while men never synthesized detectable levels of anti‐SSB, anti‐calpastatin or IgG anti‐alpha‐fodrin autoantibodies. In addition, anti‐CCP autoantibodies were found in low percentages of pSS patients (4% F/18% M). The absence of autoantibodies does not exclude the diagnosis of pSS in men that will be based mainly on the anatomopathological findings of a minor salivary gland biopsy. Positivity of anti‐60‐kDa SSA, anti‐SSB, anti‐calpastatin, IgA and IgG anti‐alpha‐fodrin antibodies is not associated with pSS clinical and biological severity.     

Anti‐citrullinated glucose‐6‐phosphate isomerase peptide antibodies in patients with rheumatoid arthritis are associated with HLA‐DRB1 shared epitope alleles and disease activity

To identify and characterize anti‐citrullinated glucose‐6‐phosphate isomerase (GPI) peptide antibodies in patients with rheumatoid arthritis (RA). Nine GPI arginine‐bearing peptides in human GPI protein were selected and cyclic citrullinated GPI peptides (CCG‐1–9) were constructed. Samples were obtained from RA (n = 208), systemic lupus erythematosus (SLE) (n = 101), Sjögren's syndrome (SS; n = 101) and healthy controls (n = 174). Antibodies against CCG‐1–9 were measured, and anti‐citrullinated α‐enolase‐1 (CEP‐1), ‐cyclic citrullinated peptides (CCP) and ‐GPI proteins antibodies were also examined. Patients with RA were genotyped for HLA‐DRB1. The numbers of shared epitope (SE) alleles were counted and compared with those of the autoantibodies. Rabbit GPI was citrullinated with rabbit peptidylarginine deiminase and immunoblot analysis of RA sera performed. The levels of autoantibodies were compared before and after treatment with TNF antagonists in 58 RA patients. Anti‐CCG‐2, ‐4 and ‐7 antibodies were detected in 25·5, 33·2 and 37·0% patients with RA, respectively, and these antibodies were very specific for RA (specificity, 98·1–99·7%). Altogether, 44·2, 86·1 and 13·9% of RA sera were positive for anti‐CEP‐1, ‐CCP and ‐GPI protein antibodies, respectively. Anti‐CCG‐2, ‐4 and ‐7 antibodies were correlated with anti‐CCP and anti‐CEP‐1 antibodies and with the presence of HLA‐DRB1 SE alleles. Citrullinated GPI protein was detected using RA sera. Treatment with tumour necrosis factor antagonists reduced significantly the levels of anti‐CCG‐2 and ‐7 but not of anti‐CEP‐1 antibodies. This is the first report documenting the presence of anti‐CCG antibodies in RA. Anti‐CCG‐2 and ‐7 antibodies could be considered as markers for the diagnosis of RA and its disease activity.     

Comparison of chemiluminescence microparticle immunoassay,indirect immunofluorescence assay,linear immunoassay and multiple microbead immunoassay detecting autoantibodies in systemic lupus erythematosus

The aim of study was to detect antinuclear antibodies (ANA) using indirect immunofluorescence assay (IIFA), linear immunoassay (LIA), chemiluminescence microparticle immunoassay (CMIA), multiple microbead immunoassay (MBI) and to compare these four methods in the performance of diagnosing systemic lupus erythematosus (SLE). Serum ANA were detected in 147 SLE cases and 42 healthy controls (HCs). The sensitivity, specificity, accuracy, positive predictive value and agreement, the area under the curve of four methods in diagnosing were calculated. Finally, a diagnostic model through logistic regression was constructed. The sensitivity of CMIA and IIFA in diagnosing SLE was 89.08% and 89.12%, higher than other two methods (P < .01), while highest specificity lied in CMIA (95.24%) and LIA (95.24%). The accuracy was highest in CMIA (91.01%), and lowest in LIA (83.07%). CMIA and the other three methods had good agreement, especially with LIA (κ = .798, 95% CI, 0.708-0.88). ANA-IIFA (OR = 1.016, P < .001) and anti-SSA antibodies (OR = 1.017, P = .043) were finally included in the SLE diagnostic model, with AUC value of 0.964 (95% CI, 0.936-0.991). SLE patients exhibited 14 various ANA patterns, especially AC-1, AC-4, and AC-5. Antibodies against SSA and dsDNA were mostly seen with AC-1 and AC-4 patterns, while antibodies against RNP, Sm, SSA, dsDNA, nucleosome and PO were most frequently observed with AC-5 pattern in SLE. CMIA method is a reliable screening test for detections of antibodies related to SLE. Using ANA-IIFA and anti-SSA antibodies by CMIA can discriminate SLE patients from HCs effectively.     

Self‐dsDNA in the pathogenesis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic and poly‐aetiological autoimmune disease characterized by the production of antibodies to autologous double‐stranded DNA (dsDNA) which serve as diagnostic and prognostic markers. The defective clearance of apoptotic material, together with neutrophil extracellular traps (NETs), provides abundant chromatin or self‐dsDNA to trigger the production of anti‐dsDNA antibodies, although the mechanisms remain to be elucidated. In SLE patients, the immune complex (IC) of dsDNA and its autoantibodies trigger the robust type I interferon (IFN‐I) production through intracellular DNA sensors, which drives the adaptive immune system to break down self‐tolerance. In this review, we will discuss the potential resources of self‐dsDNA, the mechanisms of self‐dsDNA‐mediated inflammation through various DNA sensors and its functions in SLE pathogenesis.     

Cytokine induction by circulating immune complexes and signs of in-vivo complement activation in systemic lupus erythematosus are associated with the occurrence of anti-Sjögren's syndrome A antibodies

Circulating immune complexes (IC) and levels of IC‐induced cytokines have been correlated with complement activation and autoantibody profiles in systemic lupus erythematosus (SLE). SLE sera were analysed concerning levels of immune complexes (IC), classical complement function and different antinuclear and anti‐C‐reactive protein (CRP) autoantibodies. Blood mononuclear cells from healthy donors were stimulated with isolated IC and production of interleukin (IL)‐10, IL‐6 and IL‐12p40 was measured. Functional experiments revealed that increased levels of IC‐induced cytokines were associated with both increased classical complement activation and the occurrence of anti‐Sjögren's syndrome A (SSA) and anti‐SSB but not other autoantibodies. Biochemical measurement of circulating IC showed that the degree of complement activation and the occurrence of anti‐SSA were synergistically associated with levels of circulating IC in SLE sera, as complement activation was a prerequisite for the enhancing effect of anti‐SSA. Anti‐CRP was associated with complement activation, but not with other autoantibodies. Our results indicate that anti‐SSA and possibly anti‐SSB antibodies influence IC formation and subsequent IC‐induced cytokine induction, and that they thereby participate in the inflammatory process in active SLE.     

Relationship between natural and infection‐induced antibodies in systemic autoimmune diseases (SAD): SLE,SSc and RA

Infection or vaccine‐induced T cell‐dependent immune response and the subsequent high‐affinity neutralizing antibody production have been extensively studied, while the connection between natural autoantibodies (nAAbs) and disease‐specific antibodies has not been thoroughly investigated. Our goal was to find the relationship between immunoglobulin (Ig)M and IgG isotype nAAbs and infection or vaccine‐induced and disease‐related autoantibody levels in systemic autoimmune diseases (SAD). A previously described indirect enzyme‐linked immunosorbent assay (ELISA) test was used for detection of IgM/IgG nAAbs against citrate synthase (anti‐CS) and F4 fragment (anti‐F4) of DNA topoisomerase I in 374 SAD samples, with a special focus on systemic lupus erythematosus (SLE) (n = 92), rheumatoid arthritis (n = 73) and systemic sclerosis (n = 157) disease groups. Anti‐measles IgG and anti‐dsDNA IgG/IgM autoantibodies were measured using commercial and in‐house indirect ELISA tests. In all SAD groups the anti‐measles IgG‐seropositive cases showed significantly higher anti‐CS IgG titers (P = 0·011). In anti‐dsDNA IgG‐positive SLE patients, we detected significantly higher levels of anti‐CS and anti‐F4 IgG nAAbs (P = 0·001 and < 0·001, respectively). Additionally, we found increased levels of IgM isotypes of anti‐CS and anti‐F4 nAAbs in anti‐dsDNA IgM‐positive SLE patients (P = 0·002 and 0·016, respectively). The association between IgG isotypes of pathogen‐ or autoimmune disease‐related antibodies and the IgG nAAbs may underscore the immune response‐inducible nature of the diseases investigated. The relationship between protective anti‐dsDNA IgM and the IgM isotype of anti‐F4 and anti‐CS may provide immunoserological evidence for the beneficial roles of nAAbs in SLE patients.