CRISPR-Cas immunity is repressed by the LysR-type transcriptional regulator PigU

Bacteria protect themselves from infection by bacteriophages (phages) using different defence systems, such as CRISPR-Cas. Although CRISPR-Cas provides phage resistance, fitness costs are incurred, such as through autoimmunity. CRISPR-Cas regulation can optimise defence and minimise these costs. We recently developed a genome-wide functional genomics approach (SorTn-seq) for high-throughput discovery of regulators of bacterial gene expression. Here, we applied SorTn-seq to identify loci influencing expression of the two type III-A Serratia CRISPR arrays. Multiple genes affected CRISPR expression, including those involved in outer membrane and lipopolysaccharide synthesis. By comparing loci affecting type III CRISPR arrays and cas operon expression, we identified PigU (LrhA) as a repressor that co-ordinately controls both arrays and cas genes. By repressing type III-A CRISPR-Cas expression, PigU shuts off CRISPR-Cas interference against plasmids and phages. PigU also represses interference and CRISPR adaptation by the type I-F system, which is also present in Serratia. RNA sequencing demonstrated that PigU is a global regulator that controls secondary metabolite production and motility, in addition to CRISPR-Cas immunity. Increased PigU also resulted in elevated expression of three Serratia prophages, indicating their likely induction upon sensing PigU-induced cellular changes. In summary, PigU is a major regulator of CRISPR-Cas immunity in Serratia.

Heterologous pulcherrimin production in Saccharomyces cerevisiae confers inhibitory activity on Botrytis conidiation

Pulcherrimin is an iron (III) chelate of pulcherriminic acid that plays a role in antagonistic microbial interactions, iron metabolism, and stress responses. Some bacteria and yeasts produce pulcherriminic acid, but so far, pulcherrimin could not be produced in Saccharomyces cerevisiae. Here, multiple integrations of the Metschnikowia pulcherrima PUL1 and PUL2 genes in the S. cerevisiae genome resulted in red colonies, which indicated pulcherrimin formation. The coloration correlated positively and significantly with the number of PUL1 and PUL2 genes. The presence of pulcherriminic acid was confirmed by mass spectrometry. In vitro competition assays with the plant pathogenic fungus Botrytis caroliana revealed inhibitory activity on conidiation by an engineered, strong pulcherrimin-producing S. cerevisiae strain. We demonstrate that the PUL1 and PUL2 genes from M. pulcherrima, in multiple copies, are sufficient to transfer pulcherrimin production to S. cerevisiae and represent the starting point for engineering and optimizing this biosynthetic pathway in the future.

An OmpW-dependent T4-like phage infects Serratia sp. ATCC 39006

Serratia sp. ATCC 39006 is a Gram-negative bacterium that has been used to study the function of phage defences, such as CRISPR-Cas, and phage counter-defence mechanisms. To expand our phage collection to study the phage-host interaction with Serratia sp. ATCC 39006, we isolated the T4-like myovirus LC53 in Ōtepoti Dunedin, Aotearoa New Zealand. Morphological, phenotypic and genomic characterization revealed that LC53 is virulent and similar to other Serratia, Erwinia and Kosakonia phages belonging to the genus Winklervirus. Using a transposon mutant library, we identified the host ompW gene as essential for phage infection, suggesting that it encodes the phage receptor. The genome of LC53 encodes all the characteristic T4-like core proteins involved in phage DNA replication and generation of viral particles. Furthermore, our bioinformatic analysis suggests that the transcriptional organization of LC53 is similar to that of Escherichia coli phage T4. Importantly, LC53 encodes 18 tRNAs, which likely compensate for differences in GC content between phage and host genomes. Overall, this study describes a newly isolated phage infecting Serratia sp. ATCC 39006 that expands the diversity of phages available to study phage-host interactions.

Approaches for bacteriophage genome engineering

In recent years, bacteriophage research has been boosted by a rising interest in using phage therapy to treat antibiotic-resistant bacterial infections. In addition, there is a desire to use phages and their unique proteins for specific biocontrol applications and diagnostics. However, the ability to manipulate phage genomes to understand and control gene functions, or alter phage properties such as host range, has remained challenging due to a lack of universal selectable markers. Here, we discuss the state-of-the-art techniques to engineer and select desired phage genomes using advances in cell-free methodologies and clustered regularly interspaced short palindromic repeats-CRISPR associated protein (CRISPR-Cas) counter-selection approaches.

POS1400 CLINICAL EVIDENCE OF THE DIFFERENCE IN CIRCULATING CALPROTECTIN LEVELS BETWEEN RHEUMATOID ARTHRITIS AND HEALTHY INDIVIDUALS, NON-INFLAMMATORY ARTHRITIS OR OTHER INFLAMMATORY ARTHRITIS: A SYSTEMATIC LITERATURE REVIEW AND META-ANALYSIS

Background

Rheumatoid arthritis (RA) is a systemic autoimmune disease mainly characterized by a chronic inflammation of the joints. Early diagnosis and treatment with disease-modifying antirheumatic drugs (DMARDs) is essential to prevent or slow down the structural damage. Diagnosis might be difficult in patients with mild and unspecific clinical signs and symptoms though. A differential diagnosis in patients presenting arthritis is needed for an appropriate patient management.

Acute-phase reactants (ESR or CRP) are non-specific inflammatory biomarkers used to aid in the diagnosis of RA and to assess disease activity. In the recent years, studies published have shown that calprotectin may be an alternative biomarker of active inflammatory disorders as well as a prognostic or monitoring biomarker.

Objectives

To collect all available evidence on the difference between circulating calprotectin (cCalpro) levels in rheumatoid arthritis (RA) patients and other control populations such as healthy individuals (HI), osteoarthritis (OA), psoriatic arthritis (PsA) or spondyloarthritis (SpA).

Methods

Electronic databases searches (Scopus, Pubmed and Cochrane Library), complemented by registry and hand searching, were conducted (February 4th, 2021) to identify fully paired studies comparing cCalpro levels in RA and HI, non-inflammatory arthritis (NIA), or other inflammatory arthritis.

As recommended by Cochrane, the Hedge´s standardized mean difference (SMD) and its 95% confidence intervals were used to synthetize the difference in cCalpro levels from studies using different matrices (serum or plasma) or laboratory methods. Sample size, mean and standard deviation of each group were extracted from the individual studies to conduct a random-effects model meta-analysis in STATA MP v17.0. When cCalpro levels were reported in median and range or inter-quartile, a formula was used to estimate the mean and standard deviation.

Sensitivity analysis, subgroup analyses and meta-regression analyses on matrix type (serum or plasma) and cCalpro commercial test were performed, when feasible, to investigate heterogeneity.

Results

The systematic review retrieved 27 studies comparing cCalpro levels between RA and controls. One study reported cCalpro levels in three different RA and HI cohorts. Most of RA and controls were age and gender matched. Calprotectin was measured in serum in 72,4% of the comparisons. Thirteen different commercial calprotectin tests and four homemade tests were used.

In 21 studies cCalpro levels were measured in 2678 RA and 1096 HI. cCalpro levels were significantly higher in RA than in HI (SMD=2,13;95%CI=1,27-2,98;p<0,0001), and significant heterogeneity was observed. A meta-regression on matrix and assay manufacturer indicated that 22% of the between-study variance might be explained by the type of calprotectin test used.

Five studies compared cCalpro levels in 207 RA and 187 NIA (78,57% OA). cCalpro levels were significantly higher in RA than in NIA (SMD=2,914;95% CI=0,957-4,872;p=0,0035), significant heterogeneity was observed.

cCalpro levels in 1217 RA and 411 PsA patients were reported in 5 studies. cCalpro levels were slightly higher in RA than in PsA (SMD=0,54; 95%CI=0,424-0,656; p<0,0001), while no significant heterogeneity was observed.

A comparison between cCalpro levels in RA and SpA was included in 4 studies. cCalpro levels were slightly higher in RA than in SpA (SMD=0,35; 95%CI=0,129-0,576; p=0,0020), and no significant heterogeneity was observed.

Conclusion

In this systematic review and meta-analysis, rheumatoid arthritis patients showed significantly higher circulating calprotectin levels than healthy individuals, non-inflammatory arthritis, psoriatic arthritis and spondyloarthritis. Pooled standardized mean difference between groups should be interpretated with cautious due to substantial heterogeneity or small number of studies.

Disclosure of Interests

Carmen Andalucia Employee of: Werfen, Roger Albesa Employee of: Werfen, Michael Mahler Employee of: Werfen

POS0747 ANTI-PHOSPHATIDYLSERINE/PROTHROMBIN ANTIBODIES AND VASCULAR EVENTS ASSOCIATE POSITIVELY WITH HLA-DRB1*13 AND NEGATIVELY WITH HLA-DRB1*03 IN SLE

Background

Anti-phosphatidylserine/prothrombin antibodies (anti-PS/PT) associate with thrombotic events (1). HLA-DRB1 alleles contribute to the occurrence of conventional antiphospholipid antibodies (aPL), including anti-beta2glycoprotein-I (beta2GPI) and anti-cardiolipin (CL) (2).

Objectives

We investigated associations between anti-PS/PT and HLA-DRB1 alleles and thrombosis in patients with SLE. Conventional aPL were included for comparison.

Methods

We included 341 consecutive Swedish SLE patients, with information on general cardiovascular risk factors, including blood lipids, lupus anticoagulant (LAC) and thrombotic events. Anti-PS/PT, anti-beta2GPI and anti-CL of IgA/G/M isotypes were quantified in parallel using particle-based multi-analyte technology. The 99th percentiles among 162 age- and sex-matched populations controls were used as cutoffs. HLA-DRB1 typing was performed using sequence-specific primer PCR.

Results

Anti-PS/PT antibodies associated positively with HLA-DRB1*13 (odds ratio [OR] 2.7, P=0.002), whereas anti-beta2GPI and anti-CL antibodies associated primarily with HLA-DRB1*04 (OR 2.5, P=0.0005; Table 1). These associations remained after adjustment for other significant HLA-DRB1 alleles identified in Table 1 (Figure 1a and b) also for LAC (Figure 1c), and also after adjustment for age and gender (not shown). HLA-DRB1*13, but not DRB1*04, remained as an independent risk factor for thrombosis after adjustment for significant HLA alleles (Figure 1d), and also after adjustment for cardiovascular risk factors in stepwise regression (not shown). Mediation analysis showed that 31.3% of the HLA-DRB1*13-related risk for thrombosis was mediated by anti-PS/PT positivity. HLA-DRB1*03, on the other hand, associated negatively with thrombotic events (Figure 1d) as well as with all aPL (Figure 1a-c). HLA-DRB1*03 had thrombo-protective effect in aPL positive patients (Figure 1d). Additionally, HLA-DRB1*03 positivity was associated with a favourable lipid profile regarding high-density lipoprotein (median 1.4 vs. 1.2 mmol/L, p=0.02) and triglycerides (median 0.9 vs 1.1 mmol/L, p=0.04); whereas no other HLA-DRB1 alleles showed any associations to lipid levels.

Table 1.

Frequency of individual HLA DRB1 and associations with antibody phenotypes. Odds ratios (OR) and confidence intervals (CI) for being antibody positive given a specific HLA allele and corresponding p values were calculated using Chi2 tests, with significant associations underlined.

HLA DRB1HLA-DRB1 n (%) total patientsAnti-PS/PT positive (any isotype) n=48OR (95%CI); PAnti-β2GPI or anti-CL positive (any isotype) n=96OR (95%CI); P*0141 (12.9%)4 (8.3%)0.6 (0.2-1.7); 0.311 (11.4%)0.8 (0.4-1.7); 0.6*03147 (46.5%)13 (27.1%)0.4 (0.2-0.7); 0.00433 (34.4%)0.5 (0.3-0.8); 0.006*0494 (29.7%)18 (37.5%)1.6 (0.8-2.9); 0.241 (42.7%)2.5 (1.5-4.1); 0.0005*0728 (8.9%)6 (12.5%)1.5 (0.6-4); 0.49 (9.4%)1 (0.4-2.4); 0.9*0828 (8.9%)6 (12.5%)1.6 (0.6-4.3); 0.39 (9.4%)1.2 (0.5-2.7); 0.7*099 (2.8%)1 (2.1%)0.7 (0.1-5.5); 0.72 (2.1%)0.6 (0.1-3.0); 0.5*107 (2.2%)0 (0)NA2 (2.1%)0.9 (0.2-4.6); 0.9*1127 (8.5%)6 (12.5%)1.6 (0.6-4.3); 0.38 (8.3%)0.9 (0.4-2.2); 0.8*127 (2.2%)0 (0)NA1 (1%)0.4 (0.05-3.7); 0.4*1379 (25%)21 (43.7%)2.7 (1.4-5.2); 0.00233 (34.3%)2 (1.2-3.4%); 0.01*146 (1.9%)2 (4.2%)3.7 (0.6-23); 0.12 (2.1%)1.4 (0.2-8.9); 0.8*15118 (37.3%)12 (48%)0.5 (0.2-0.9); 0.04527 (28.1%)0.5 (0.3-0.9); 0.01*168 (2.5%)1 (2.1%)0.8 (0.09-6.4); 0.84 (4.2%)2.2 (0.5-9.2); 0.2

Conclusion

HLA-DRB1*13 confers risk for both anti-PS/PT and thrombotic events in SLE. The association between HLA-DRB1*13 and thrombosis is largely, but not entirely, mediated through anti-PS/PT. Due to the negative association of HLA-DRB1*03 with aPL and the positive association with favourable lipid levels, HLA-DRB1*03 seems to identify a subgroup of SLE patients with reduced vascular risk.

References

[1]Elbagir S et al. Lupus 2021;30(8):1289.

[2]Lundström E et al. Ann Rheum Dis 2013;72:1018.

Disclosure of Interests

Sahwa Elbagir: None declared, Lina M. Diaz-Gallo: None declared, Giorgia Grosso: None declared, Agneta Zickert: None declared, Iva Gunnarsson: None declared, Michael Mahler Employee of: Dr Mahler is employee of Werfen., Elisabet Svenungsson Speakers bureau: Dr Svennungson has obtained speaker’s fees from Janssen., Grant/research support from: Dr Svennungson has obtained research grant from Merck., Johan Rönnelid Speakers bureau: Dr Rönnelid has given paid lectures for Thermo Fisher Scientific., Consultant of: Dr Rönnelid has been a member of the Scientific Advisory Board for Thermo Fisher Scientific.

POS0464 IS IT POSSIBLE TO IDENTIFY INDIVIDUALS AT IMMINENT-RISK OF SUB-CLINICAL JOINT INVOLVEMENT?

Background:

In anti-CCP antibody (Ab) positive at-risk individuals with MSK symptoms but without clinical synovitis, the detection of ultrasound (US) subclinical inflammation is associated with an increased risk of progression to inflammatory arthritis (IA) 1. Studies suggest that in these at-risk individuals, MSK symptoms develop before subclinical joint inflammation occurs on US. As such, anti-CCP Ab positive individuals with MSK symptoms in the absence of clinical or sub-clinical inflammation may be at the critical time-point for preventive treatments, before joint inflammation occurs and eventually becomes established (i.e., before the ‘second-hit’ in RA pathogenesis); however, identifying these individuals is challenging.

Objectives:

To identify, in second generation anti-CCP Ab (CCP2+) at-risk individuals with MSK symptoms, but without clinical or sub-clinical synovitis, predictors of US sub-clinical synovitis.

Methods:

In 186 CCP2+ at-risk individuals with normal baseline US scan (i.e., no synovitis or bone erosions), and a complete dataset, US data were analyzed at 6, 12 months, then annually until occurrence of IA. US synovitis was identified according to the EULAR/OMERACT definitions2. Relevant demographic (age and gender), clinical [early morning stiffness (EMS), tenderness in the small joints of the hands] and serological [anti-CCP2 Ab level, third generation anti-CCP Ab (CCP3) and rheumatoid factor (RF)] data were collected at baseline. Regression analyses, Kaplan-Meier analysis and Log-Rank test were performed.

Results:

US synovitis was detected in ≥1 longitudinal US scan in 69/186 (37.1%) at-risk individuals (median time to first developing US synovitis: 53 weeks, IQR 27.0-105.8; median number of joints with US synovitis: 2.0, IQR 1.0-2.0). As shown in Table 1, only anti-CCP3 Ab were significantly associated with development of US sub-clinical synovitis in the multi-variable analysis while borderline results were observed with age.

Table 1.

Regression analyses for the development of US synovitis.

Univariable analysisMultivariableanalysisOR (95% CI)p-valueOR (95% CI)p-valueGender (male)1.02 (0.52-2.02)0.95//Age1.03 (1.01-1.06)<0.011.03 (1.00-1.06)0.03Tenderness in the hands0.86 (0.46-1.61)0.64//EMS1.60 (0.87-2.95)0.13//Anti-CCP2 Ab (high titre)2.79 (1.37-5.67)<0.011.20 (0.50-2.89)0.69Anti-CCP3+4.44 (2.28-8.66)<0.013.30 (1.39-7.89)<0.01RF+2.96 (0.46-1.61)0.011.45 (0.68-3.11)0.33

CCP2+ individuals with positive anti-CCP3 Ab show a significantly reduced sub-clinical synovitis-free survival rate compared with individuals with negative anti-CCP3 Ab (Figure 1). At 1- and 2-year follow-up, respectively 23.3% and 38.3% of individuals with dual CCP2/CCP3 positivity developed sub-clinical synovitis on longitudinal scans, compared with 8.4% and 13.3% of CCP2+ individuals with negative anti-CCP3 Ab (p=0.01) (Figure 1a).

Similar results were observed in the subgroup of high level CCP2+ individuals. At 1- and 2-year follow-up, respectively 24.5% and 39.4% of high level CPP2/anti-CCP3+, but only 6.1% and 15.2% of CCP2+ individuals with negative anti-CCP3 developed sub-clinical synovitis on longitudinal scans (p<0.01) (Figure 1b).

Figure 1.

Kaplan-Meier analysis shows US sub-clinical synovitis free survival time in CCP2+ at-risk individuals.

Conclusion:

In anti-CCP2+ at-risk individuals with MSK symptoms, anti-CCP3 antibodies improve prediction of imminent development of subclinical joint inflammation. This may represent the critical time-point for interventions to prevent the onset of joint disease. This is also a unique population for investigating the drivers of joint involvement in the development of RA.

References:

[1]Duquenne L, et al. The Role of Ultrasound Across the Inflammatory Arthritis Continuum: Focus on “At-Risk” Individuals. 2020.

[2]D’Agostino MA, et al. Scoring ultrasound synovitis in rheumatoid arthritis: a EULAR-OMERACT ultrasound taskforce — Part 1: definition and development of a standardised, consensus-based scoring system. 2017.

Disclosure of Interests:

Andrea Di Matteo Grant/research support from: This study was conducted while Andrea Di Matteo was an ARTICULUM Fellow., Kulveer Mankia Speakers bureau: KM reports personal fees from Abbvie, UCB and Eli Lilly (all <$10.000), outside the submitted work., Grant/research support from: Research grants from BMS, Eli Lilly (all <$10.000), Laurence Duquenne: None declared, Edoardo Cipolletta: None declared, Jacqueline Nam: None declared, Leticia Garcia-Montoya: None declared, Richard Wakefield Speakers bureau: RJW has received honoraria from Abbvie, Novartis and GE for ultrasound related educational activities (all <$10.000)., Michael Mahler Employee of: MM is employee of Inova Diagnostics, commercializing CCP3, Paul Emery Speakers bureau: PE reports consultant fees from BMS, AbbVie, Gilead, Galapagos, Lilly, MSD, Pfizer, Novartis, Roche, and Samsung outside the submitted work (all <$10.000)., Grant/research support from: He also reports research grants from UCB, AbbVie, Lilly, Novartis, BMS, Pfizer, MSD and Roche, outside the submitted work. PE is National Institute for Health Research (NIHR) Biomedical Research Centre (BRC) director and BRC funds supported this work. Leticia Garcia-Montoya and Laurence Duquenne are NIHR BRC fellows.

OP0118 DECIPHERING THE ANTI-PROTEIN-ARGININE DEIMINASE (PAD) RESPONSE IDENTIFIES PAD1 AND PAD6 AS NOVEL AUTOANTIGENS IN RHEUMATOID ARTHRITIS

Background:

Protein-arginine deiminase (PAD) 4 enzymes play a central role in the pathogenesis of rheumatoid arthritis (RA) and represents an antigenic target. Among the five known family members (PAD1, PAD2, PAD3, PAD4 and PAD6), only PAD2, PAD3 and PAD4 have been described to have autoantigenic properties. Furtheremore, very little is known on the the isotype usage of these autoantibodies. Understanding the molecular basis of the anti-PAD antibody reponse has the potential to open novel approaches for precision medicine in RA.

Objectives:

The objectives of this study were to screen for the presence of antibodies to the five PAD family members and to evaluate the isotype usage of the anti-PAD4 response in RA.

Methods:

First, we developed a panel for the detection of anti-PAD IgG based on a particle-based multi-analyte technology (PMAT), that utilized paramagnetic particles coupled with the different human recombinant PAD proteins (PAD1, PAD2, PAD3, PAD4 and PAD6) and anti-human IgG conjugate. This panel was used to test sera from RA patients (n=33) and non-RA controls (n=36). The controls were comprised of apparently healthy individuals (n=10), and patients with infectious diseases (n=10), systemic lupus erythematosus (n=7), systemic sclerosis (n=9) and Sjogren’s syndrome (n=1). Next, the PAD4-coupled beads were tested with anti-human IgM, IgA and IgG conjugates on an extended cohort of RA patients (n=62) and the same non-RA controls.

Results:

All five anti-PAD IgG (Figure 1) demonstrated the ability to discriminate between RA patients and controls. At greater than 90% specificity, anti-PAD4 IgG, followed by anti-PAD3 IgG, showed the best diagnostic performance. Significantly higher levels of the five antibodies were observed in RAvs.controls (p-values of 0.0041, <0.0001, 0.0014, 0.0039, and 0.0140 for anti-PAD1, 2, 3, 4 and 6, respectively). Significant correlation was observed between all the antibodies, with the highest between anti-PAD1 and anti-PAD4 (Spearman´srho=0.87,p<0.0001) and the lowest between anti-PAD4 and anti-PAD2 (Spearman’srho=0.38,p=0.0015) and anti-PAD4 and anti-PAD6 (Spearman’srho=0.38,p=0.0011). While principal component analysis (PCA) (Figure 2) showed an association between all anti-PAD antibodies, there was further discrimination that displayed closer association between anti-PAD1, 3 and 4 on one hand, and between anti-PAD2 and 6. For the extended testing of anti-PAD4 with IgG, IgA and IgM, all three isotypes were identified in the sera of RA patients. Higher levels of the three isotypes were observed in RA patients with erosive disease when compared with the patients without erosion, but this association was only significant for anti-PAD4 IgA (p=0.0086).

Figure 1.

Receiver operating characteristics (ROC) analysis of the discrimination between rheumatoid arthritis (RA) and controls of IgG to protein-arginine deiminase (PAD) 1, PAD2, PAD3, PAD4 and PAD6. The area under the curve (AUC) values are shown in brackets for each biomarker.Abbreviations:TPF: true positive fraction; FPF: false positive fraction

Figure 2.

Two dimensional principal component analysis (PCA) plot of the anti-PAD levels in RA patients (n=33) and controls (n=36). Anti-PAD1, 3 and 4 have the main contribution to PC1, which explains 51.7% of the variance, and anti-PAD2 and 6 to PC2, that represents 20.8% of it.Abbreviations:PC: principal component

Conclusion:

Our study is the first to describe PAD1 and PAD6 as novel antigenic targets in RA and to demostrate that the anti-PAD4 B-cell immune response uses all three isotypes (IgG, IgA and IgM). The strong and significant association between anti-PAD4 IgA and joint erosion is of particular clinical relevance.

Disclosure of Interests:

Laura Martinez-Prat Employee of: I am an employee of Inova Diagnostics, an in vitro diagnostics company., Mary Ann Aure Employee of: I am an employee of Inova Diagnostics, an in vitro diagnostics company., Chelsea Bentow Employee of: I am an employee of Inova Diagnostics, an in vitro diagnostics company., David Lucia Employee of: I am an employee of Inova Diagnostics, an in vitro diagnostics company., Marcos Lopez-Hoyos Consultant of: Inova Diagnostics, an in vitro diagnostics company., Michael Mahler Employee of: I am an employee of Inova Diagnostics, an in vitro diagnostics company.

Updated results from the phase 3 HELIOS study of ibrutinib, bendamustine, and rituximab in relapsed chronic lymphocytic leukemia/small lymphocytic lymphoma

We report follow-up results from the randomized, placebo-controlled, phase 3 HELIOS trial of ibrutinib+bendamustine and rituximab (BR) for previously treated chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) without deletion 17p. Overall, 578 patients were randomized 1:1 to either ibrutinib (420 mg daily) or placebo, in combination with 6 cycles of BR, followed by ibrutinib or placebo alone. Median follow-up was 34.8 months (range: 0.1-45.8). Investigator-assessed median progression-free survival (PFS) was not reached for ibrutinib+BR, versus 14.3 months for placebo+BR (hazard ratio [HR] [95% CI], 0.206 [0.159-0.265]; P < 0.0001); 36-month PFS rates were 68.0% versus 13.9%, respectively. The results are consistent with the primary analysis findings (HR = 0.203, as assessed by independent review committee, with 17-month median follow-up). Median overall survival was not reached in either arm; HR (95% CI) for ibrutinib+BR versus placebo: 0.652 (0.454-0.935; P = 0.019). Minimal residual disease (MRD)-negative response rates were 26.3% for ibrutinib+BR and 6.2% for placebo+BR (P < 0.0001). Incidence of treatment-emergent adverse events (including grades 3-4) were generally consistent with the initial HELIOS report. These long-term data support improved survival outcomes and deepening responses with ibrutinib+BR compared with BR in relapsed CLL/SLL.

Clinical and serological associations of autoantibodies to the Ku70/Ku80 heterodimer determined by a novel chemiluminescent immunoassay

BACKGROUND

Autoantibodies targeting Ku, an abundant nuclear protein with DNA helicase activity, have been reported in patients with systemic autoimmune rheumatic diseases. Little is known about the clinical associations of anti-Ku antibodies, especially when novel diagnostic technologies are used. The objective of the present study was to analyse the prevalence of anti-Ku antibodies in different medical conditions using a novel chemiluminescent immunoassay.

PATIENTS AND METHODS

Serum samples from adult patients with systemic lupus erythematosus (SLE, n=305), systemic sclerosis (SSc, n=70) and autoimmune myositis patients (AIM, n=109) were the primary focus of the study. Results were compared with disease controls (rheumatoid arthritis, RA, n=30; infectious diseases, n=17) and healthy individuals (n=167). In addition, samples submitted for routine autoantibody testing from patients referred to a rheumatology clinic (n=1078) were studied. All samples were tested for anti-Ku antibodies by QUANTA Flash Ku chemiluminescent immunoassay (research use only, Inova Diagnostics, San Diego, USA) using full length recombinant human Ku. SLE patient samples were also tested for other autoantibodies. Clinical data of anti-Ku antibody positive patients (high titres) were obtained by retrospective chart review.

RESULTS AND FINDINGS

In the disease cohorts, 30/305 (9.8%) SLE, 3/70 (4.3%) systemic sclerosis and 4/109 (3.7%) autoimmune myositis (AIM) patients were positive, respectively. The four positive AIM patients had an overlap myositis syndrome that included two patients with SLE. The three systemic sclerosis (SSc) positive samples had diagnoses of SSc/SLE overlap, diffuse cutaneous SSc, and early edematous phase SSc. In the control cohorts, 2/170 (1.2%) healthy individuals (all low titre), 0/30 (0.0%) (RA) and 0/17 (0.0%) infectious disease patients were positive. The area under the curve values were: 0.75 for SLE vs. controls, 0.68 for SSc vs. controls and 0.37 for AIM vs.

CONTROLS

In the rheumatology clinic referral cohort, 12/1078 (1.1%) were positive for anti-Ku antibodies, nine showing low and three high titres. The diagnoses of the three high positive anti-Ku positive patients were: probable SLE, mixed connective tissue disease (MCTD) and ANA positive RA.

CONCLUSION

Anti-Ku antibodies detected by chemiluminescent immunoassay are most prevalent in SLE. When found in AIM and SSc, they were associated with overlap syndrome and early SSc.

Development and multi-center evaluation of a novel immunoadsorption method for anti-DFS70 antibodies

OBJECTIVE

Antinuclear antibodies (ANA) represent a hallmark in the diagnosis of ANA-associated rheumatic diseases (AARD). However, anti-DFS70 antibodies are present in a higher portion of the healthy individuals (HI) than in patients with AARD. Consequently, we developed a novel, highly specific indirect immunofluorescence (IIF) method that blocks anti-DFS70 antibodies from binding to HEp-2 cells and to evaluate the method in a multi-center study.

METHODS

A total of 18 samples from systemic lupus erythematosus patients (SLE, n = 7) and HI (n = 11) were used for the initial development of the immunoadsorption method. For the multi-center evaluation, samples with a dense fine speckled (DFS) pattern (n = 99) were collected at three different sites based on their established IIF screening procedure at the respective laboratories. Additionally, four characterized samples with established clinically relevant IIF patterns (centromere, nucleolar, speckled, homogeneous) were blended in five different ratios (10%, 25%, 50%, 75%, 90%) with a sample positive for anti-DFS70 antibodies, which by itself showed a dense fine speckled (DFS) IIF pattern. All samples were tested by IIF with NOVA Lite HEp-2 ANA and NOVA Lite HEp-2 Select on the NOVA View® instrument, and also tested by QUANTA Flash DFS70 chemiluminescent immunoassay (CIA) for confirmation of anti-DFS70 antibodies (Inova Diagnostics, San Diego, CA, USA).

RESULTS

For the development of the immunoadsorption method, only 1/7 ANA-positive samples from SLE patients, but 8/10 ANA-positive samples from healthy individuals turned negative using the immunoadsorption. Subsequently, 73/99 (73.7%) of the DFS pattern samples were positive by CIA for anti-DFS70 antibodies showing a strong quantitative Spearman's correlation (rho = 0.57 (95% CI, 0.39-0.71, p < 0.0001)) between light intensity units (LIU) measured by NOVA View and CIA. Intensities measured with NOVA Lite HEp-2 and NOVA Lite HEp-2 Select demonstrated significantly lower intensity values after inhibition with DFS70 antigen (p < 0.0001). When samples were processed to mimic samples with mixed patterns (DFS + clinically relevant pattern), the new immunoadsorption method demonstrated that all clinically relevant patterns remained unchanged whereas the LIUs from NOVA View analysis significantly decreased after inhibition (p < 0.0001).

CONCLUSION

The data showed that the NOVA Lite HEp-2 Select kit effectively inhibits anti-DFS70 antibody binding to its cellular target antigen.

Autoantibodies to domain 1 of beta 2 glycoprotein I determined using a novel chemiluminescence immunoassay demonstrate association with thrombosis in patients with antiphospholipid syndrome

INTRODUCTION

Antibodies to the domain 1 of beta 2 glycoprotein I (β2GPI-D1) have been suggested as a risk marker for thrombosis in patients with the antiphospholipid syndrome (APS). This cross-sectional study aimed to analyze the clinical utility of a novel chemiluminescence assay for the detection of anti-β2GPI-D1 antibodies.

PATIENTS AND METHODS

Sera collected from patients with primary or secondary APS (n = 106; 72 with and 34 without history of thrombosis) and controls (n = 272) were tested for anti-β2GPI-D1 IgG by chemiluminescence assay (QUANTA Flash) and by two anti-β2GPI IgG assays (QUANTA Lite and QUANTA Flash β2GPI IgG).

RESULTS

Anti-β2GPI-D1 IgG titers were significantly higher in patients with thrombosis (P = 0.0032) than those without. At the cut-off of 20 units, which yielded a 99.5% specificity, 24 of 72 (34.9%) patients with thrombosis and four of 34 (11.8%) without thrombosis were anti-β2GPI-D1 IgG positive (odds ratio, OR = 4.0). By further optimizing the cut-off specifically for correlation with thrombosis, 20.8% of the patients with thrombosis and 2.9% of the patients without thrombosis were positive (OR = 8.7). The ORs were significantly lower for antibodies to the full-length β2GPI by either the chemiluminescence assay or ELISA. Using the anti-β2GPI chemiluminescence assay, the OR was 2.3 (recommended cut-off of 20 CU) or 4.1 (optimal cut-off 164.6 CU). Using the anti-β2GPI ELISA, the OR was 2.7 (recommended cut-off of 20 units) or 3.7 (optimal cut-off 7.6 units).

CONCLUSION

These data indicate that anti-β2GPI-D1 IgG are present more frequently and in higher titers in APS patients with thrombotic complications than in those without.The novel β2GPI-D1 chemiluminescence assay appears to be superior to full-length β2GPI assays for the risk assessment of thrombotic events in APS patients.

International multi-center evaluation of a novel chemiluminescence assay for the detection of anti-dsDNA antibodies

OBJECTIVE

Anti-double stranded desoxyribonucleic acid (anti-dsDNA) antibodies are considered fairly specific for systemic lupus erythematosus (SLE) and their quantification is useful for the clinical management of SLE patients. We assessed the diagnostic performance of the QUANTA Flash dsDNA chemiluminescent immunoassay (CIA) in comparison to an ELISA, using patients from five participating countries. The main focus was to evaluate the correlation between anti-dsDNA antibody results from the CIA and global SLE disease activity, as measured by the SLE Disease Activity Index 2000 (SLEDAI-2K).

PATIENTS AND METHODS

A total of 1431 samples (SLE, n = 843; disease controls, n = 588) from five countries (Canada, USA, Portugal, Sweden and Spain) were tested with QUANTA Flash dsDNA (Inova Diagnostics, San Diego, CA, USA). Data obtained with the QUANTA Lite dsDNA SC ELISA (Inova Diagnostics) were available for samples from three sites (Canada, USA and Sweden, n = 566). The SLEDAI-2K scores were available for 805 SLE patients and a cut-off of > 4 was used to define active disease.

RESULTS

QUANTA Flash dsDNA had a sensitivity of 54.3% for the diagnosis of SLE, combined with 89.8% specificity. Anti-dsDNA antibody levels were significantly higher (p < 0.0001) in active SLE (SLEDAI-2K > 4; n = 232; median value 83.0 IU/mL) versus the inactive patients (n = 573; median value 22.3 IU/mL), and the SLEDAI-2K scoring correlated with their dsDNA antibody levels (Spearman's rho = 0.44, p < 0.0001). Similar but less pronounced findings were also found for the ELISA, in relation to disease activity.

CONCLUSIONS

The QUANTA Flash dsDNA assay showed good clinical performance in a large international multi-center study. Additionally, the strong correlation between anti-dsDNA antibody results and SLEDAI-2K scores supported the potential utility of QUANTA Flash dsDNA for monitoring disease activity.

Socioeconomic status and lifestyle behaviours in cancer survivors: smoking and physical activity

PURPOSE

Smoking cessation and increased physical activity (pa) have been linked to better outcomes in cancer survivors. We assessed whether socioeconomic factors influence changes in those behaviours after a cancer diagnosis.

METHODS

As part of a cross-sectional study, a diverse group of cancer survivors at the Princess Margaret Cancer Centre (Toronto, ON), completed a questionnaire about past and current lifestyle behaviours and perceptions about the importance of those behaviours with respect to their health. The influence of socioeconomic indicators on smoking status and physical inactivity at 1 year before and after diagnosis were assessed using multivariable logistic regression with adjustment for clinico-demographic factors.

RESULTS

Of 1222 participants, 1192 completed the smoking component. Of those respondents, 15% smoked before diagnosis, and 43% of those smokers continued to smoke after. The proportion of survivors who continued to smoke increased with lower education level (p = 0.03). Of the 1106 participants answering pa questions, 39% reported being physically inactive before diagnosis, of whom 82% remained inactive afterward. Survivors with a lower education level were most likely to remain inactive after diagnosis (p = 0.003). Lower education level, household income, and occupation were associated with the perception that pa had no effect or could worsen fatigue and quality of life (p ≤ 0.0001).

CONCLUSIONS

In cancer survivors, education level was a major modifier of smoking and pa behaviours. Lower socioeconomic status was associated with incorrect perceptions about pa. Targeting at-risk survivors by education level should be evaluated as a strategy in cancer survivorship programs.

From autoantibody research to standardized diagnostic assays in the management of human diseases – report of the 12th Dresden Symposium on Autoantibodies

Testing for autoantibodies (AABs) is becoming more and more relevant, not only for diagnosing autoimmune diseases (AIDs) but also for the differentiation of defined AID subtypes with different clinical manifestations, course and prognosis as well as the very early diagnosis for adequate management in the context of personalized medicine. A major challenge to improve diagnostic accuracy is to harmonize or even standardize AAB analyses. This review presents the results of the 12th Dresden Symposium on Autoantibodies that focused on several aspects of improving autoimmune diagnostics. Topics that are addressed include the International Consensus on ANA Patterns (ICAP) and the International Autoantibody Standardization (IAS) initiatives, the optimization of diagnostic algorithms, the description and evaluation of novel disease-specific AABs as well as the development and introduction of novel assays into routine diagnostics. This review also highlights important developments of recent years, most notably the improvement in diagnosing and predicting the course of rheumatoid arthritis, systemic sclerosis, idiopathic inflammatory myopathies, and of autoimmune neurological, gastrointestinal and liver diseases; the potential diagnostic role of anti-DFS70 antibodies and tumor-associated AABs. Furthermore, some hot topics in autoimmunity regarding disease pathogenesis and management are described.

Patient preference: a comparison of electronic patient-completed questionnaires with paper among cancer patients

In this study, we compared cancer patients preference for computerised (tablet/web-based) surveys versus paper. We also assessed whether the understanding of a cancer-related topic, pharmacogenomics is affected by the survey format, and examined differences in demographic and medical characteristics which may affect patient preference and understanding. Three hundred and four cancer patients completed a tablet-administered survey and another 153 patients completed a paper-based survey. Patients who participated in the tablet survey were questioned regarding their preference for survey format administration (paper, tablet and web-based). Understanding was assessed with a 'direct' method, by asking patients to assess their understanding of genetic testing, and with a 'composite' score. Patients preferred administration with tablet (71%) compared with web-based (12%) and paper (17%). Patients <65 years old, non-Caucasians and white-collar professionals significantly preferred the computerised format following multivariate analysis. There was no significant difference in understanding between the paper and tablet survey with direct questioning or composite score. Age (<65 years) and white-collar professionals were associated with increased understanding (both P = 0.03). There was no significant difference in understanding between the tablet and print survey in a multivariate analysis. Patients overwhelmingly preferred computerised surveys and understanding of pharmacogenomics was not affected by survey format.

Highlights on novel technologies for the detection of antibodies to Ro60, Ro52, and SS-B

OBJECTIVE

We aimed to compare a chemiluminescent immunoassay (CIA, QUANTA Flash) on BIO-FLASH with a multiplex flow immunoassay (MFI) on BioPlex 2200 for the detection of antibodies to Ro60, Ro52, and SS-B.

METHODS

The study included 241 samples, from patients suffering from systemic autoimmune diseases (n = 108) as well as disease controls (n = 133). All samples were tested for anti-Ro52, anti-Ro60, and anti-SS-B (La) antibodies on QUANTA Flash (INOVA Diagnostics, San Diego, USA) and BioPlex 2200 (Bio-Rad Laboratories Inc., Hercules, USA). Discrepant samples were tested by two independent methods: BlueDot/ANA and QUANTRIX Microarray (both D-tek, Belgium).

RESULTS

The overall qualitative agreements were 95.4% (95% confidence interval, CI 92.0-97.7%) for anti-Ro52, 98.8% (95% CI 96.4-99.7%) for anti-Ro60, and 91.7% (95% CI 87.5-94.9%) for anti-SS-B antibodies. There were 34 discrepant samples among all assays (20 anti-SS-B, 11 anti-Ro52, 3 anti-Ro60). 30/33 of retested samples (by D-tek dot blot) agreed with the QUANTA Flash results. Similar findings were obtained with QUANTRIX Microarray kit.

CONCLUSION

QUANTA Flash and BioPlex 2200 show good qualitative agreement. The clinical performances were similar for anti-Ro52 and anti-Ro60 autoantibodies while differences were observed for anti-SS-B (La) antibodies.

Severe hepatocellular dysfunction in obstetric cholestasis related to combined genetic variation in hepatobiliary transporters

Obstetric cholestasis (OC) is a cholestatic disorder with a prominent genetic background including variation in diverse hepatobiliary lipid transporters, such as ABCB4 (phospholipids) and ABCB11 (bile salts). Given a marked hepatocellular dysfunction in an OC patient indicated by > 40-fold rise in alanine aminotransferase activity and minor gamma-glutamyl transpeptidase increases, we performed genotyping of candidate gene variants associated with adult cholestatic phenotypes. Genetic analysis revealed the heterozygous ABCB4 mutation p.R590Q, the ABCB11 variant p.V444A and the lithogenic ABCG8 variant p.D19H. Aggregation of multiple hepatobiliary transporter variants is rare in OC, and may cooperate to negatively modulate hepatobiliary transport capacities.

The common adiponutrin variant p.I148M does not confer gallstone risk but affects fasting glucose and triglyceride levels

Recently the common adiponutrin (PNPLA3) polymorphism p.I148M has been identified as a genetic determinant of severe forms of non-alcoholic fatty liver disease and alcoholic liver disease. Additionally, insulin resistance - linked to the development of non-alcoholic steatohepatitis - increases the risk of developing gallstones. Here we assessed whether the PNPLA3 p.I148M (c.444 C-G) polymorphism affects glucose and lipid levels and increases gallstone risk. We analysed 229 individuals with gallstones from 108 families (age 24-80 years, BMI 17-55 kg/m(2)) and 258 gallstone-free controls (age 20-70 years, BMI 14-43 kg/m(2)). Fasting glucose, triglyceride and cholesterol serum levels were determined. The p.I148M polymorphism was genotyped using a PCR-based assay with 5'-nuclease and fluorescence detection. Case-control association tests and nonparametric linkage (NPL) analysis in sib-pairs were performed. Individuals carrying the [GG] genotype had significantly (P<0.0001) higher median fasting glucose levels as compared to [GC] and [CC] carriers. After adjustment for multiple testing, we detected a trend for an association between triglyceride levels and variant adiponutrin in gallstone patients (P=0.032), and gallstone cases carrying the genotype [CC] presented with significantly higher triglyceride levels than the corresponding controls (P<0.003). No significant effects on cholesterol metabolism were detected. Neither genotype distributions nor NPL scores provided evidence for association or linkage between the PNPLA3 variant and gallstones. In conclusion, homozygous carriers of the PNPLA3 risk allele display higher fasting glucose. Although this adiponutrin variant may affect triglyceride homeostasis, it does not increase the risk of cholelithiasis.

Novel diagnostic and clinical aspects of anti-PCNA antibodies detected by novel detection methods

Autoantibodies targeting the proliferating cell nuclear antigen have been considered as a specific biomarker for systemic lupus erythematosus, and were historically identified by indirect immunofluorescence and then confirmed by other more specific immunoassays. Our objective was to investigate the anti-PCNA immune response in various disease conditions. Unselected sera referred to a clinical diagnostic laboratory and other sera from various diseases cohorts and controls were tested for anti-PCNA antibodies by enzyme-linked immunosorbent assay (ELISA), line immunoassay (LIA) and an addressable laser bead assay (ALBIA) using full-length human proliferating cell nuclear antigen. Two out of 2500 sequential, unselected sera (0.07%) referred to a diagnostic laboratory for autoantibody analysis showed a proliferating cell nuclear antigen-like staining pattern. Good agreement was found between ELISA, ALBIA and LIA. At cut-off values resulting in 100% specificity, 52.5% (ELISA), 42.5% (ALBIA) and 35% (LIA) of samples with a proliferating cell nuclear antigen-like indirect immunofluorescence staining pattern were positive. In the indirect immunofluorescence proliferating cell nuclear antigen immunoblot (IB)-positive group, anti-PCNA antibodies were frequently accompanied by anti-Ro52, and in the indirect immunofluorescence PCNA-negative but LIA PCNA-positive group by various other autoantibodies. The prevalence of anti-PCNA antibodies was highest in Sjögren’s syndrome (5.0%). In conclusion, the proliferating cell nuclear antigen-like staining pattern was rarely found (0.07%) in sequential, unselected sera. Further, indirect immunofluorescence is not an accurate screening method to identify anti-PCNA antibodies as their presence may be masked by other autoantibodies. The specific association of anti-PCNA antibodies with systemic lupus erythematosus was not confirmed in our study. Lupus (2010) 19, 1527—1533.

Diverse humoral autoimmunity to the ribosomal P proteins in systemic lupus erythematosus and hepatitis C virus infection

Autoantibodies to the three ribosomal P proteins (Rib-P) are specifically found in 10% to 40% of systemic lupus erythematosus (SLE) patients. Most anti-Rib-P autoantibodies bind to a C-terminal epitope shared by all three Rib-P proteins P0, P1 and P2. In the present study, we shed more light on the humoral autoimmune response to the Rib-P antigen as it occurs in autoimmunity and infectious disease. In a mutational analysis of the major C-terminal epitope, we verified the key role of phenylalanine residues Phe ( 111 ) and Phe ( 114 ) for binding of most anti-Rib-P serum autoantibodies present in SLE sera (n = 28). By nuclear magnetic resonance (NMR) investigation of a peptide comprising the C-terminal 22 amino acids, we observed hallmarks for alpha-helical secondary structure of the Rib-P epitope core (GFGLFD). Based on NMR data and on SPOT epitope analysis, we propose a structural model of the Rib-P major epitope, which displays Phe ( 111 ) and Phe ( 114 ) on one side of the helix. Apart from that, two sera from the hepatitis C virus (HCV) control group (n = 68) were found to contain antibodies specific for P2, but not for the other Rib-P proteins. Using a SPOT peptide array scanning the P2 amino acid sequence, we identified reactivity with two distinct epitopes (residues 21-35 and 41-55 of Rib-P2) shared by both HCV sera. We conclude that anti-Rib-P autoreactivity occurs in SLE, Chagas' disease (CD) and-as firstly described here-during HCV infection. Anti-Rib-P reactivity in SLE sera primarily depends on Phe ( 111 ) and Phe ( 114 ) of the alpha-helical C-terminal epitope. In contrast, anti-Rib-P autoantibodies in HCV infection mainly recognize epitopes within the N-terminal half of ribosomal P2.

Serological and Clinical Characterization of Anti-dsDNA and Anti-PM/Scl Double-Positive Patients

Antibodies to double-stranded desoxyribonucleic acid (dsDNA) and to the polymyositis/scleroderma (PM/Scl) complex are regarded as serological markers for systemic lupus erythematosus (SLE) and PM/Scl overlap syndrome, respectively. In a previous study, serum samples were identified that contained antibodies specific for both dsDNA and PM/Scl. Fourteen of these sera were available for more detailed investigation including the autoantibody profile as determined by several methods including an addressable laser bead assay, Crithidia luciliae indirect immunofluorescence test (CLIFT) and a PM1-Alpha ELISA. Moreover, 300 samples from connective tissue disease patients and 30 PM/Scl positive samples were screened for anti-dsDNA(+)/PM/Scl(+) specimens by CLIFT, dsDNA ELISA, and PM1-Alpha ELISA. We confirmed anti-dsDNA and anti-PM/Scl reactivity in 2/7 samples from the previous study. One sample had also anti-chromatin and anti-SS-A reactivity and the second sample was oligoreactive. In addition, 2/300 (0.7%) unselected samples from connective tissue disease patients were identified with anti-dsDNA and anti-PM/Scl reactivity. In a panel of PM1-Alpha positive samples (n = 30) collected regardless of the diagnosis of the patients, no anti-dsDNA reactivity was found. All anti-dsDNA(+)/anti-PM/Scl(+) patients identified fulfilled sufficient criteria to be classified as definite SLE and also had at least one feature of systemic sclerosis (i.e., sclerodactyly and/or Raynaud's phenomenon). Only 1/4 patients had clinical evidence of dermatomyositis. The combination of anti-dsDNA(+)/anti-PM/Scl(+) in patients suffering from connective tissue disease is less frequently found than previously described when newer assays are used. Clinically, anti-dsDNA(+)/anti-PM/Scl(+) patients may define a small subgroup of SLE patients with additional features of systemic sclerosis.

Environment as a Critical Factor for the Pathogenesis and Outcome of Gastrointestinal Disease: Experimental and Human Inflammatory Bowel Disease and Helicobacter-Induced Gastritis

Environmental factors play an important role in the manifestation, course, and prognosis of diseases of the gastrointestinal tract such as inflammatory bowel disease (IBD) and Helicobacter pylori-induced gastritis. These two disease complexes were chosen for a discussion of the contribution of environmental factors to the disease outcome in humans and animal models. Dissecting complex diseases like IBD and Helicobacter-induced gastritis has shown that the outcome of disease depends on the allelic constellation of a host and the microbial and physical environments. Host alleles predisposing to a disease in one genomic and/or environmental milieu may not be deleterious in other constellations; on the other hand, microbes can have different effects in different hosts and under different environmental conditions. The impact of the complex interaction between host genetics and environmental factors, particularly microflora, also underlines the importance of a defined genetic background and defined environments in animal studies and is indicative of the difficulties in analyzing complex diseases in humans.

Improved serological differentiation between systemic lupus erythematosus and mixed connective tissue disease by use of an SmD3 peptide-based immunoassay

Autoantibodies to the Sm antigens are specifically found in 5 to 30% of patients with systemic lupus erythematosus (SLE) depending on the detection system and the patient group. Several immunoassays designed for research and diagnostic laboratory use have been developed. The autoantigens employed in these tests include purified native proteins, recombinant polypeptides, and synthetic peptides. In the present study, we compared the clinical accuracy of anti-Sm autoantibody assays from commercial suppliers including different conventional enzyme-linked immunosorbent assay (ELISA) systems based on purified Sm antigens, an addressable laser bead assay and a newly developed anti-Sm peptide assay. Although the clinical sensitivity of all assays under investigation was comparable, relatively poor correlations and significant differences in specificity were found with a patient cohort of 150 patients. The sensitivity and specificity were 10 and 94%, respectively, for the anti-Sm ELISA from Euroimmun, 10 and 90%, respectively, for the QuantaLite Sm (INOVA), 12 and 88%, respectively, for the Sm assay in the Varelisa ReCombi ANA profile (Pharmacia Diagnostics), 10 and 94%, respectively, for the QuantaPlex Sm (INOVA), and 12 and 100%, respectively, for the new SmD3 peptide-based ELISA (Varelisa Sm Antibodies). The majority of positive test results within the control groups were found in patients with mixed connective tissue disease. Based on the results, we conclude that the detection of anti-Sm antibodies strongly depends both on the nature of the antigen and on the detection system. Finally, we conclude that the recently identified SmD peptide containing a symmetrical dimethylarginine at position 112 of D3 represents a promising tool for the detection of a highly specific subpopulation of anti-Sm antibodies.

Technical and clinical evaluation of anti-ribosomal P protein immunoassays

Autoantibodies to the three ribosomal phospho (-P) proteins P0, P1, P2, referred to as Rib-P, are specifically found in 10-40% of patients with systemic lupus erythematosus. The variations in the observed frequency of these autoantibodies is related to a number of factors such as the test system used to detect the antibodies. Several immunoassays that were designed for research and diagnostic laboratory use have been developed. The autoantigens employed in these tests include native proteins, recombinant polypeptides, and synthetic peptides. In this study, we compared the technical and clinical accuracy of anti-Rib-P antibody assays from different commercial suppliers including ELISA systems and a novel addressable laser bead assay (from Euroimmun, MBL, Pharmacia Diagnostics, INOVA). Although the assays from all suppliers used in this study performed well in the technical part of the study, relatively poor correlations and significant differences in the clinical accuracy were found. Based on the results, we conclude that the detection of anti-Rib-P antibodies strongly depends on both the nature of the antigen and the detection system. We recommend that anti-Rib-P assays should be standardized on an international level. The Varelisa Rib-P profile and the addressable laser bead Rib-P assays represent promising tools and platforms for the detection of anti-Rib-P antibodies in the future.