Performance of commercial SARS-CoV-2 wild-type and Omicron BA.1 antibody assays compared with pseudovirus neutralization tests

BACKGROUND

Commercially available ELISA-based antibody tests are used to approximate vaccination success against SARS-CoV-2 in at-risk patients, but it is unclear whether they correlate with neutralization of the Omicron variant.

METHODS

269 serum samples of a cohort of 44 non-immunosuppressed participants and 65 MTX-treated rheumatic patients taken before and after COVID-19 booster vaccinations were measured using COVID-19 antibody testing systems with wild-type and Omicron BA.1 antigens developed by three different manufacturers (surrogate virus neutralization test cPass, and binding antibody tests QuantiVac and SeraSpot), as well as with a pseudovirus neutralization test (pVNT). The pVNT was considered the gold standard for determining the presence and level of anti-SARS-CoV-2 antibodies.

RESULTS

All three wild-type ELISAs showed excellent test performance compared with wild-type neutralization in pVNT. However, out of 56 samples without Omicron BA.1 neutralization in pVNT, 71.4% showed positive results in at least one and 28.6% in all three wild-type ELISAs at the manufacturer-defined cut-offs. Omicron ELISAs showed either decreased specificity (57.1% and 55.4% for binding ELISAs) or sensitivity (51.2% in cPass) compared to Omicron neutralization in pVNT. The proportion of any false positive results among all samples decreased from 26.5% before to 3.2% after booster vaccination, however binding antibody test specificities remained below 70%.

CONCLUSIONS

We found a poorer test performance of new Omicron antibody test systems compared to wild-type tests in detecting neutralizing antibodies against the corresponding SARS-CoV-2 variants. Decisions for booster vaccination or passive immunization of at-risk patients should not be based solely on antibody test results.

AB1155 PAUSING METHOTREXATE IMPROVES IMMUNOGENICITY OF COVID-19 VACCINATION IN PATIENTS WITH RHEUMATIC DISEASES

Background

Several research groups have recently described a reduced vaccination response to COVID-19 vaccination under methotrexate (MTX) (1,2). The increase in humoral immune response when pausing MTX two weeks after vaccination has already been described for influenza vaccination (3). However, data regarding MTX-hold during COVID-19 vaccination are still lacking.

Objectives

To study the effect of MTX and its discontinuation on the humoral immune response after COVID-19 vaccination in patients with autoimmune rheumatic diseases (AIRD).

Methods

In this retrospective study, neutralising SARS-CoV-2 antibodies were measured after second vaccination in 64 rheumatic patients on methotrexate therapy, 31 of whom temporarily paused medication without a fixed regimen. The control group consisted of 21 AIRD patients without immunosuppressive medication.

Results

MTX patients showed a significantly lower mean antibody response compared to AIRD patients without immunosuppressive therapy (71.8 % vs 92.4 %, p<0.001). For patients taking MTX, age correlated negatively with immune response (r=-0.49; p<0.001). All nine patients with antibody levels below the cut-off were older than 60 years. Patients who held MTX during at least one vaccination showed significantly higher mean neutralising antibody levels after second vaccination, compared to patients who continued MTX therapy during both vaccinations (83.1 % vs 61.2 %, p=0.001). This effect was particularly pronounced in patients older than 60 years (80.8 % vs 51.9 %, p=0.001). The impact of the time period after vaccination was greater than of the time before vaccination with the critical cut-off being 10 days.

Conclusion

MTX reduces the immunogenicity of SARS-CoV-2 vaccination in an age-dependent manner. Our data further suggest that holding MTX for at least 10 days after vaccination significantly improves the antibody response in patients over 60 years of age.

References

[1]Haberman RH, Herati R, Simon D, et al. Methotrexate hampers immunogenicity to BNT162b2 mRNA COVID-19 vaccine in immune-mediated inflammatory disease. Annals of the Rheumatic Diseases 2021

[2]Mahil SK, Bechman K, Raharja A, et al. The effect of methotrexate and targeted immunosuppression on humoral and cellular immune responses to the COVID-19 vaccine BNT162b2: a cohort study. The Lancet Rheumatology 2021;3(9):e627-e37.

[3]Park JK, Choi Y, Winthrop KL, et al. Optimal time between the last methotrexate administration and seasonal influenza vaccination in rheumatoid arthritis: post hoc analysis of a randomised clinical trial. Annals of the rheumatic diseases 2019;78(9):1283-84.

Acknowledgements

We would like to thank Tanja Braun and Vera Höhne-Zimmer for their

support in obtaining the ethics vote and for their organisational support.

Disclosure of Interests

None declared

OP0078 ALTERED IMMUNOLOGICAL CIRCADIAN RHYTHMS AND THE EFFECT OF TREATMENT WITH GLUCOCORTICOIDS ON CIRCADIAN RHYTHMS OF IMMUNE CELLS IN PATIENTS WITH RHEUMATOID ARTHRITIS: BRING BACK THE RHYTHM

Background

In rheumatoid arthritis (RA), pain, joint swelling, and stiffness follow a clear circadian pattern. Most of these symptoms are most pronounced in the early morning and primarily attributed to elevated levels of the key proinflammatory cytokines IL-6 and TNFα, which usually peak before clinical symptoms worsen (1). Synthetic glucocorticoids (GCs) are among the most prescribed drugs in the management of patients with RA. GCs have effects on almost every immune cell. GCs suppress expression of various cytokines, including IL-1β, TNFα, IL-6, and GM-CSF. Moreover, circadian rhythms of immune cells are known to be influenced by GCs. For example, GCs govern in part the rhythm of circulating CD4+ and CD8+ T cells.

Objectives

To identify circadian patterns for optimization of diagnosis and treatment strategies, we conducted a clinical study comparing healthy donors (HD) and patients with RA in terms of circadian rhythms. We examined the effect of treatment with GCs on circadian immune rhythms in patients with RA.

Methods

We recruited 12 HD and 13 patients with active RA (DAS28≥4.0) who either were (n=8) or, for comparison, were not (n=5) under current treatment with GCs. Their biological clock was synchronized for a week before the study day by a scheduled sleep and mealtime regimen. On the study day, participants were provided with regular meals, allowed to eat snacks ad libitum and carry passive activities. We collected blood samples every two hours over a period of 24 hours. The absolute number of circulating immune cells, clock gene expression, and serum cytokine levels were measured with TruCount, qPCR, and multiplex suspension assay, respectively.

Results

Peripheral regulatory T cells are circadian in HD and RA, but the number was notably reduced in RA (Table 1). CD8+ T cells, CD14+ monocytes, and CD19+ B cells lost their circadian rhythms in RA, but these rhythms were restored with GC treatment. Circulating NK and NK T cells, which are not diurnal in HD, exhibited circadian fluctuations in RA. GC treatment suppressed diurnal pathological circulation rhythms of NK and NK T cells by reducing the amplitude by half. In monocytes, BMAL1, PER1, PER2, and REVERBA are only circadian in HD. GC restored the rhythms of PER2 and REVERBA. CRY1 expression showed diurnal variation in RA, but not in HD. IL-6 exhibited a circadian pattern in both groups, and GC treatment showed no significant effects on IL-6. Serum IL-4, IL-5, and MIP3α showed circadian variation in HD only. The following cytokines were notably elevated in RA-patients: IFNγ, MIP1α, MIP1β, IL-1β, IL-2, IL-17A, and IL-21. GC reduced the expression of IL-10 significantly in RA.

Table 1.

Circadian rhythms in the cellular, gene, and protein levels in HD, RA, and RA with ongoing GC treatment

ComparisonCircadian / GC impactCirculating immune cellsClock genes in monocytesSerum cytokinesHD vs. RANon-circadian in HD and RA-CLOCK, CRY2, DBP, RORAFractaline, IFNγ, CXCL11, GM-CSF, MIP1α, MIP1β, IL-1β, IL-2, IL-4, IL-7, IL-8, IL-10, IL-12, IL-13, IL-17A, IL-21, IL-23Circadian in HD and RACD3+, CD4+, regulatory T cellsPER3IL-6Circadian in HDCD8+ T cells, CD14+ monocytes, CD19+ B cellsBMAL1,PER1, PER2, REVERBAIL-4, IL-5, MIP3αCircadian in RANK cells, NK T cellsCRY1-RA vs. GCs-treated RARestorative effect by GCCD8+ T cells, CD19+ B cellsPER2, REVERBA-Enhancing effect by GCregulatory T cellsPER3, CRY1-Dampening effect by GCNK T cells, NK cells--

Conclusion

In patients with RA, we found a certain loss of circadian rhythms and the establishment of “inflammatory” rhythms. GC treatment in patients with RA resulted in three different types of effects on circadian rhythms at immune cell level: restoration, amplification, and attenuation. In conclusion, these findings provide new insights into the pathophysiology of circadian rhythms in RA that could be used to optimize diagnosis and treatment.

References

[1]Clocking in: chronobiology in rheumatoid arthritis.Buttgereit, Frank, et al. 2015, Nature Reviews Rheumatology, Vol. 11, pp. 349–356.

Acknowledgements

We thank all participants for their contribution. We thank our clinical study team: Manuela Jakstadt, Lisa Ehlers, Alexandra Damerau, Annamarie Lang, Moritz Pfeiffenberger, Gabriela May, and Pierre-Louis Krauß.

Disclosure of Interests

None declared.

Refractory mixed proliferative and membranous lupus nephritis treated with the topoisomerase I inhibitor irinotecan as add-on therapy

OBJECTIVE

To evaluate the safety and effects of irinotecan, an inhibitor of topoisomerase I, on refractory lupus nephritis.

METHOD

A patient with refractory lupus nephritis under medication with mycophenolic acid, prednisolone, and hydroxychloroquine was treated with add-on low-dose irinotecan. Irinotecan was applied every fourth week at a dose of 50 mg/m² for four cycles followed by 100 mg/m² for another eight cycles. Renal function and anti-double-stranded DNA antibodies as well as blood count for evaluation of side effects were assessed during the treatment with irinotecan.

RESULTS

Before starting the treatment with irinotecan, a urine protein/creatinine ratio of 1298 mg/g was determined. This declined to 613 mg/g after four cycles with 50 mg/m² irinotecan and was further reduced to 198 mg/g when using the higher dose of irinotecan. Kidney function remained stable, with creatinine levels of 1.66 mg/dL at the beginning and 1.76 mg/dL at the end of treatment with irinotecan. Importantly, no side effects, such as diarrhoea or neutropenia, were observed during the entire course of treatment.

CONCLUSION

Administration of low-dose irinotecan as add-on medication for the treatment of refractory lupus nephritis was shown to be safe. Clinical trials are needed to determine whether irinotecan can improve kidney function and the outcome of patients with refractory lupus nephritis.

OP0256 CHOOSE WISELY: IMAGING FOR DIAGNOSIS OF AXIAL SPONDYLOARTHRITIS

Background:

To date, the European Alliance of Associations for Rheumatology (EULAR) guidelines recommend X-ray (XR) as first line imaging in axial Spondyloarthritis (axSpA) and magnetic resonance imaging (MR) if the diagnosis cannot be established by XR and clinical features. However, much knowledge has been gained recently strengthening the applicability of MR for the detection of structural lesions and raising the question, whether XR is still necessary. Also, several publications used low-dose computed tomography (CT) as reference standard and imaging test.

Objectives:

In light of this complex diagnostic situation, the aim of this study was to compare the three major modalities, XR, MR and CT of SIJ, in their diagnostic performance of axSpA and differential diagnosis in a cohort of patients with low back pain using the final judgment of the rheumatologist as standard of reference.

Methods:

163 patients (89 with axSpA; 74 with degenerative diseases) underwent XR, CT and MR. Three blinded experts categorized the imaging into axSpA, other diseases or normal in 5 separate reading rounds (XR, CT, MR, XR+MR, CT+MR, respectively). The results were compared to the clinical diagnosis. Sensitivity and specificity values for axSpA and interrater reliability were compared.

Results:

XR showed lower sensitivity and specificity (66.3%/67.6% respectively) compared to MR (82.0%/86.5%) and CT (77.5%/97.3%). Sensitivity and specificity of XR+MR was similar to MR alone (77.5% / 87.8%). However, CT+MR was superior to MR alone (75.6% / 97.3%) (see Figure). CT had the best interrater reliability (kappa = 0.875) followed by MR (0.665) and XR (0.517). CR+MR reliability was similar (0.662) compared to MR alone, while CT+MR reliability (0.732) was superior.

Figure 1.

Frequency of positive and negative findings in radiography (XR), computed tomography (CT), magnetic resonance imaging (MR) and combinations and resulting diagnostic accuracy values. SE: Sensitivity, SP: Specificity, LR-/+: negative/positive likelihood ratio.

Conclusion:

In conclusion, XR is inferior to cross-sectional imaging and should be replaced by MR or CT for differential diagnosis. While MR is the most sensitive imaging technique, it lacks specificity when compared to CT. CT alone has high diagnostic accuracy, despite being insensitive to bone marrow lesions such as fatty metaplasia or osteitis. Adding CT to MR leads to an increase in specificity at a minor expense of sensitivity.

References:

[1]Sieper J, Rudwaleit M, Baraliakos X, et al. The Assessment of SpondyloArthritis international Society (ASAS) handbook: a guide to assess spondyloarthritis. Ann Rheum Dis. 2009;68 Suppl 2:ii1-44.

[2]Mandl P, Navarro-Compán V, Terslev L, et al. EULAR recommendations for the use of imaging in the diagnosis and management of spondyloarthritis in clinical practice. Ann Rheum Dis. 2015;74(7):1327-39.

[3]Diekhoff T, Hermann KA, Greese J, et al. Comparison of MRI with radiography for detecting structural lesions of the sacroiliac joint using CT as standard of reference: results from the SIMACT study. Ann Rheum Dis. 2017.

[4]Diekhoff T, Greese J, Sieper J, Poddubnyy D, Hamm B, Hermann KA. Improved detection of erosions in the sacroiliac joints on MRI with volumetric interpolated breath-hold examination (VIBE): results from the SIMACT study. Ann Rheum Dis. 2018;77(11):1585-89.

[5]Baraliakos X, Hoffmann F, Deng X, Wang YY, Huang F, Braun J. Detection of Erosions in Sacroiliac Joints of Patients with Axial Spondyloarthritis Using the Magnetic Resonance Imaging Volumetric Interpolated Breath-hold Examination. The Journal of rheumatology. 2019;46(11):1445-49.

[6]Wu H, Zhang G, Shi L, et al. Axial Spondyloarthritis: Dual-Energy Virtual Noncalcium CT in the Detection of Bone Marrow Edema in the Sacroiliac Joints. Radiology. 2019;290(1):157-64.

Disclosure of Interests:

Torsten Diekhoff Speakers bureau: Canon MS, Roche, Novartis, MSD, Grant/research support from: Assessment of Spondyloarthritis International Society, Iris Eshed: None declared, Felix Radny: None declared, Katharina Ziegeler: None declared, Fabian Proft: None declared, Juliane Greese: None declared, Dominik Deppe: None declared, Robert Biesen: None declared, Kay-Geert Hermann: None declared, Denis Poddubnyy: None declared

POS0744 A NEGATIVE INTERFERON BIOMARKER CD169 / SIGLEC-1 RULES OUT SYSTEMIC LUPUS ERYTHEMATOSUS

Background:

While there have been advances in the therapy of systemic lupus erythematosus (SLE) in recent years, there have been no major new findings in SLE biomarkers [1, 2]. Type I interferon (IFN) plays a pivotal role in the pathogenesis of SLE [3]. In 2008, we first described CD169 / SIGLEC-1 (sialic acid-binding immunoglobulin-like lectin-1), an interferon-induced adhesion molecule on monocytes in SLE patients [4]. For over five years SIGLEC-1 has been routinely assessed in our clinic.

Objectives:

To evaluate and compare the diagnostic utility of the type I IFN induced SIGLEC-1 with established biomarkers in the initial diagnosis of the disease.

Methods:

We analyzed retrospectively 232 patients who were on suspicion of SLE at Charité University Hospital Berlin between October 2015 and September 2020. Patients underwent full clinical characterization, and biomarkers were determined in the routine laboratory. Based on the final diagnosis, we divided patients into two groups: A) initial diagnosis of SLE and B) Non-SLE mimicking condition.

Results:

In 76 patients (32.3 %) SLE was confirmed by fulfilling the EULAR / ACR 2019 classification criteria [5]. SIGLEC-1 was dramatically increased in patients with an initial diagnosis of SLE compared to patients without SLE (p<0.0001). For a threshold of 2500 molecule per monocyte, a sensitivity of 98.7 %, a specificity of 82.1 %, a negative predictive value (NPV) of 99.2 %, and a positive predictive value (PPV) of 72.8 % were calculated for SIGLEC-1. Adjusted to the prevalence of SLE in Germany (36.7 per 100,000 inhabitants [6]) NPV and PPV turned out to > 99.9 % and 0.2 %. We further aimed to compare not only the performance of the tests at a given cutoff but also across all possible measured values. Therefore, we conducted ROC curves analyses (see figure 1). The area under the curve (AUC) of SIGLEC-1 test was significantly higher than that of ANA test (AUC=0.88, p=0.031), C3 (AUC = 0.83, p=0.001), C4 (AUC=0.83, p=0.002), but not than that of the Anti-dsDNA ELISA (AUC=0.90, p=0.163).

Conclusion:

Our study shows that IFN activity is a hallmark at the onset of the disease and that the interferon biomarker SIGLEC-1 is valuable to rule out SLE in suspected cases.

References:

[1]Ostendorf L, Burns M, Durek P, Heinz GA, Heinrich F, Garantziotis P, Enghard P, Richter U, Biesen R, Schneider U et al: Targeting CD38 with Daratumumab in Refractory Systemic Lupus Erythematosus. N Engl J Med 2020, 383(12):1149-1155.

[2]Furie R, Rovin BH, Houssiau F, Malvar A, Teng YKO, Contreras G, Amoura Z, Yu X, Mok CC, Santiago MB et al: Two-Year, Randomized, Controlled Trial of Belimumab in Lupus Nephritis. N Engl J Med 2020, 383(12):1117-1128.

[3]Ronnblom L, Leonard D: Interferon pathway in SLE: one key to unlocking the mystery of the disease. Lupus Sci Med 2019, 6(1):e000270.

[4]Biesen R, Demir C, Barkhudarova F, Grun JR, Steinbrich-Zollner M, Backhaus M, Haupl T, Rudwaleit M, Riemekasten G, Radbruch A et al: Sialic acid-binding Ig-like lectin 1 expression in inflammatory and resident monocytes is a potential biomarker for monitoring disease activity and success of therapy in systemic lupus erythematosus. Arthritis Rheum 2008, 58(4):1136-1145.

[5]Aringer M, Costenbader K, Daikh D, Brinks R, Mosca M, Ramsey-Goldman R, Smolen JS, Wofsy D, Boumpas DT, Kamen DL et al: 2019 European League Against Rheumatism/American College of Rheumatology classification criteria for systemic lupus erythematosus. Annals of the Rheumatic Diseases 2019, 78(9):1151-1159.

[6]Brinks R, Fischer-Betz R, Sander O, Richter JG, Chehab G, Schneider M: Age-specific prevalence of diagnosed systemic lupus erythematosus in Germany 2002 and projection to 2030. Lupus 2014, 23(13):1407-1411.

Disclosure of Interests:

None declared

POS0370 TYPE I INTERFERON PATHWAY ASSAYS IN PATIENTS WITH RHEUMATIC AND MUSCULOSKELETAL DISEASES - SYSTEMATIC LITERATURE REVIEW (SLR) AND DEVELOPMENT OF CONSENSUS TERMINOLOGY FROM A EULAR TASKFORCE

Background:

The interferon (IFN) pathway is a complex system with multiple proteins and diverse downstream effects on gene and protein expression. IFNs have been implicated in multiple RMDs. Despite significant potential, IFN assays have not progressed into clinical practice.

Objectives:

To perform a SLR on IFN assays in RMDs and propose a consensus terminology.

Methods:

OvidMedline, Embase and Web of Science were searched for reports of IFN and RMDs up to October 2019. Information about the properties of assays measuring type I IFN and measures of truth were extracted and summarised. Terminology was agreed through an interactive consensus process with reference to the existing evidence.

Results:

10037 abstracts were identified. 275 fulfilled eligibility criteria, and were used for data extraction. Some used more than one technique to measure IFN-I pathway activation. Hence, 275 papers generated data on 393 methods. There was great heterogeneity in the methods used and presentation of results. IFN-I pathway activation was measured using: qPCR (n=121), immunoassays (n=101), microarray (n=69), reporter cell assay (n=38), DNA methylation (n=14), flow cytometry (n=14), cytopathic effect assay (n=11), RNA sequencing (n=9), Plaque reduction assay (n=8), Nanostring (n=5), bisulphite sequencing (n=3). All papers fulfilled Face Validity. Due to lack of gold standard for IFN-I pathway activation, evidence of criterion validity was variable. Concurrent validity was presented for n=150 assays. The terminology used to describe aspects of type I IFN pathway activation was not consistent, so a consensus terminology for IFN research (Table 1) was proposed by the taskforce.

Table 1.

Consensus terminology

TermAbbreviationDefinitionInterferonIFNProteins with anti-viral activity; IFNs are mediators of an anti-viral response. They belong to the Type I, Type II and Type III IFN families.Type I interferonIFN-IThe IFNs alpha, beta, omega, kappa, epsilon, secreted by any nucleated cell, and binding to the IFNAR, which is expressed on any nucleated cell.Type II interferonIFN-IIIFN gamma, mostly secreted by T cells, binding to the IFNGR, which is expressed on most leucocytes.Type III interferonIFN-IIIIFN lambda, which are structurally more similar to IL-10 but share downstream signalling and gene expression with IFN-I.Interferon-stimulated genesISGsGenes whose expression is known to be upregulated by any kind of IFN. Individual ISGs may not exclusively represent Type I IFN pathway activation.Type I Interferon pathway activationAny evidence for function of the components of the Type I IFN pathway. This includes: secretion of a Type I IFN protein, binding to the IFNAR, initiation of JAK/STAT signalling pathways, expression of IFN-stimulated genes, expression of IFN-stimulated proteins.Type I interferon pathway assayAn assay measuring one or more components of the Type I IFN pathway at a molecular or functional level.Interferon stimulated gene expression signatureA qualitative description of coordinated expression of a set of ISGs that is indicative of Type I IFN pathway activation.Interferon stimulated gene expression scoreA quantitative variable derived from expression of a defined set of ISGs that is indicative of Type I IFN pathway activation.Interferon stimulated protein scoreA variable derived from expression of a defined set of soluble biomarkers known to be upregulated by IFN, although not specific for Type I IFN.InterferonopathyMonogenic diseases in which there is constitutive Type I IFN pathway activation with a causal role in pathology. The clinical picture may resemble rheumatic musculoskeletal diseases. However, most diseases with IFN pathway activation are not Interferonopathies.

Conclusion:

Diverse methods have been reported as IFN assays and these differ in what elements of type IFN-I pathway activation they measure. The taskforce consensus terminology on type I IFN reporting should be considered for research and clinical applications.

Disclosure of Interests:

Agata Burska: None declared, Javier Rodriguez Carrio: None declared, Philip G Conaghan: None declared, Willem A Dik: None declared, Robert Biesen: None declared, Maija-leena Eloranta: None declared, Giulio Cavalli: None declared, Marianne Visser: None declared, Dimitrios Boumpas: None declared, George Bertsias: None declared, Marie Wahren-Herlenius: None declared, Jan Rehwinkel: None declared, Marie-Louise Frémond: None declared, Mary K. Crow Consultant of: AstraZeneca, Bristol Meyers Squibb, Lilly, Shannon Pharmaceuticals, Grant/research support from: Gilead, Lars Ronnblom Consultant of: AstraZeneca, Edward Vital Speakers bureau: GSK, Consultant of: AURINIA, SANDOZ, GSK, AstraZeneca, Roche, Modus, Grant/research support from: AstraZeneca, Marjan Versnel: None declared

POS0183 SIGLEC1 AS A TYPE I INTERFERON BIOMARKER IN IDIOPATHIC INFLAMMATORY MYOPATHIES

Background:

Idiopathic inflammatory myopathies (IIM) are autoimmune diseases that mainly affect skeletal muscle, lung, skin and joints. IIM can be separated into dermatomyositis (DM), inclusion body myositis (IBM), antisynthetase syndrome (AS) and immune-mediated necrotizing myopathy (IMNM). Type I interferons (IFN) are known to play a crucial role in the etiopathogenesis of some of these entities such as DM.[1] Sialic acid binding Ig-like lectin 1 (SIGLEC1, CD169) is part of the type I IFN signature found in SLE and DM and is expressed on the cell surface of monocytes. Thus, analysis of SIGLEC1 expression by flow cytometry enables a straightforward assessment of the type I IFN signature. Its utility has been shown for juvenile and adult SLE and other rheumatic diseases but not in IIM.[2,3] The assessment of the type I IFN system in clinical practice is an unmet need and, in this context, SIGLEC1 might be useful.

Objectives:

To assess SIGLEC1 expression on monocytes by flow cytometry as a type I IFN biomarker in IIM

Methods:

Pediatric and adult patients with a clinical diagnosis of DM, AS, IMNM and IBM and at least one measurement of SIGLEC1 who have been treated at the Department of Rheumatology, Charité - Universitätsmedizin Berlin between 2015 and 2020 were included in this retrospective study. Control groups of healthy individuals (n=19) and SLE patients (n=30) were included. Disease activity was assessed by Physician Global Assessment (PGA) and Childhood Myositis Assessment Scale (CMAS). SIGLEC1 expression on monocytes was analyzed by flow cytometry. Cross-sectional analyses (n=74) were performed using Mann Whitney-U test (MWU) and two-level mixed-effects linear regression model was used for longitudinal analyses (n=26, 110 visits). This study was approved by the local ethics committee of the Charité - Universitätsmedizin Berlin.

Results:

74 patients (adult/juvenile DM: n=21/n=17; AS: n=19; IMNM: n=8; IBM: n=9) were included. In cross-sectional analysis, SIGLEC1 expression was significantly upregulated in adult and juvenile DM patients with moderate to severe disease activity (PGA≥5) compared with adult/juvenile DM patients with no to moderate disease activity (PGA<5) (both p<0.001). In longitudinal analyses, SIGLEC1 correlated with disease activity in juvenile DM (SIGLEC1 vs. CMAS: betaST=-0.65; p<0.001) and adult DM (SIGLEC1 vs. PGA: betaST=0.52; p<0.001), better than Creatine Kinase (CK) (juvenile DM, CK vs. CMAS: betaST=-0.50; p<0.001; adult DM, CK vs PGA: betaST=0.17; p=0.149). In AS 42,1% of the patients showed elevated SIGLEC1 expression, while it was not upregulated in IMNM and only in two patients with IBM, who were concurrently positive for autoantibodies that affect the type I IFN system (see Figure 1).

Conclusion:

SIGLEC1 is a useful biomarker to identify an activated type I IFN system in IIM. Flow cytometry is used widely in laboratory medicine, which could facilitate the implementation of SIGLEC1 into clinical routine.

References:

[1]Gallay L, Mouchiroud G, Chazaud B. Interferon-signature in idiopathic inflammatory myopathies: Current Opinion in Rheumatology 2019;31:634–42. doi:10.1097/BOR.0000000000000653

[2]Rose T, Grutzkau A, Hirseland H, et al. IFNalpha and its response proteins, IP-10 and SIGLEC-1, are biomarkers of disease activity in systemic lupus erythematosus. Ann Rheum Dis 2013;72:1639–45. doi:10.1136/annrheumdis-2012-201586

[3]Stuckrad SL von, Klotsche J, Biesen R, et al. SIGLEC1 (CD169) is a sensitive biomarker for the deterioration of the clinical course in childhood systemic lupus erythematosus. Lupus 2020;:961203320965699. doi:10.1177/0961203320965699

Figure 1.

SIGLEC1 expression on monocytes in IIM subgroups and control groups; in IIM subgroups, patients with low disease activity (PGA<5) are marked in blue, patients with high disease activity (PGA≥5) are marked in red; mAb/cell, monoclonal antibodies bound per cell

Disclosure of Interests:

None declared

OP0300 A CROSS-SECTIONAL, MATCHED-PAIR ANALYSIS OF ACPA POSITIVE AND ACPA NEGATIVE RHEUMATOID ARTHRITIS PATIENTS COMPARING THE PREVALENCE OF OSTEOPOROSIS, FRAGILITY FRACTURES AND UNDERLYING RISK FACTORS

Background:

Rheumatoid arthritis (RA) is associated with increased systemic bone loss, leading to a high risk for fragility fractures. Especially anti-citrullinated protein antibody (ACPA) positivity is considered a risk factor for local bone erosions and systemic bone loss1.

Objectives:

The purpose of this study was to compare ACPA positive versus ACPA negative RA patients in terms of the prevalence of osteoporosis and fragility fractures and to identify differences in underlying risk factors that influence bone health.

Methods:

Rh-GIOP is an ongoing prospective observational study collecting and analyzing disease- and bone-related data from patients with chronic rheumatic diseases or psoriasis treated with glucocorticoids (GC). In this cross-sectional analysis, we performed a matched-pair analysis, matching 114 ACPA positive to 114 ACPA negative RA patients according to age (5-year-steps), sex, and body mass index (BMI, 2-unit-steps). Descriptive analyses were performed, with values displayed as mean ± standard deviation for continuous variables. Non-parametric tests were used at a two-sided significance level of 5% to compare differences in underlying and potential risk factors without adjustment for multiple testing.

Results:

At same mean age (63.9 ±10.2 years) and BMI (27.9 ±5.6kg/m2), the matched groups had a female proportion of 82.5%. APCA positive patients had a significantly longer mean disease duration (13.9 vs 9.9 years, p<0.001), a higher mean cumulative GC-dose (22.3 vs 13.2g, p<0.01) and mean duration of GC therapy (10.1 vs 6.6 years, p<0.01). There was no significant difference in the prevalence of osteoporosis as defined by dual-energy X-ray absorptiometry (DXA) (18.4 vs 20.2%), nor in the prevalence of vertebral (7.0 vs 5.3%) or non-vertebral fractures (31.6 vs 29.8%). C-reactive protein levels as a marker of disease activity were significantly higher in ACPA positive patients (mean: 8.8 vs 4.3mg/l, p= 0.02), while mean disease activity score (DAS)28 levels were slightly lower in ACPA positive patients (2.4 vs 2.7, p= 0.05). No difference in health assessment questionnaire (HAQ) score was found. RA-specific treatments were similar, especially concerning current mean daily GC-dose (6.7 vs 4.9mg/day), except for Rituximab and targeted synthetic disease modifying anti-rheumatic drugs (DMARDs) which were more commonly used in ACPA positive patients (9.6 vs 2.6%, p=0.05) and (5.3 vs 0%, p=0.029), respectively. ACPA positive patients did not differ significantly from ACPA negative patients in specific anti-osteoporotic treatment, nor in the prevalence of comorbidities or concomitant medication. There were no significant differences in bone-specific laboratory parameters.

Conclusion:

In a cross-sectional analysis of our cohort, the prevalence of osteoporosis and fragility fractures was similar between ACPA positive and ACPA negative RA patients, despite longer disease duration and GC-treatment in ACPA positive patients. This is remarkable since it implies that ACPA negative patients are at a similar risk for osteoporosis and associated fractures. Optimal management of disease activity with or without GCs may represent a mainstay in preventing disease-related comorbidities such as osteoporosis.

References:

[1]Steffen, U., Schett, G., & Bozec, A. (2019). How Autoantibodies Regulate Osteoclast Induced Bone Loss in Rheumatoid Arthritis. Frontiers in immunology, 10, 1483. doi:10.3389/fimmu.2019.01483

Disclosure of Interests:

Edgar Wiebe: None declared, Desiree Freier: None declared, Dörte Huscher: None declared, gloria dallagiacoma: None declared, Robert Biesen: None declared, Sandra Hermann: None declared, Gerd Rüdiger Burmester Consultant of: AbbVie Inc, Eli Lilly, Gilead, Janssen, Merck, Roche, Pfizer, and UCB Pharma, Speakers bureau: AbbVie Inc, Eli Lilly, Gilead, Janssen, Merck, Roche, Pfizer, and UCB Pharma, Frank Buttgereit Grant/research support from: Amgen, BMS, Celgene, Generic Assays, GSK, Hexal, Horizon, Lilly, medac, Mundipharma, Novartis, Pfizer, Roche, and Sanofi.

AB0767 PATIENTS WITH RHEUMATOID ARTHRITIS HAVE A LOWER BONE DENSITY THAN PATIENTS WITH PSORIATIC ARTHRITIS

Background:

Osteoporosis is a skeletal disease characterized by the loss of bone density resulting in an increased fracture risk. Female sex, advanced age, Caucasian ancestry, previous history of fractures, menopause and certain genetic factors predispose for osteoporosis. In addition, recent studies could prove that chronic inflammatory diseases such as Rheumatoid Arthritis (RA) and long-term treatment with higher doses of glucocorticoids (GCs) represent independent risk factors for the development of osteoporosis. On the other hand, the intake of vitamin D, a calcium-rich diet and physical exercise can be protective. Data describing the prevalence of osteoporosis in patients with other rheumatic diseases like psoriatic arthritis (PsA) are lacking.

Objectives:

We compared the prevalence of osteopenia and osteoporosis in patients with RA and PsA, respectively, based on data obtained from our ongoing prospective monocentric study Rh-GIOP investigating glucocorticoid (GC)-induced osteoporosis in patients with different rheumatic diseases (NCT02719314).

Methods:

Bone mineral density data measured by dual x-ray absorptiometry (DXA) in patients with PsA (n=92) were compared with data measured in 92 age- and gender-matched patients with RA. The results were analysed with respect to clinical and laboratory parameters such as data on GC treatment (frequency, duration defined as start of treatment until timepoint of measurement, actual and cumulative dose), csDMARD and bDMARD (including as well tsDMARDs) therapy, serological parameters (Vitamin D, alkaline phosphatase, calcium, inflammatory markers and rheumatoid factor) and functional status (e.g. Health Assessment Questionnaire (HAQ), sporting activities). Statistical analyses were performed descriptively using mean and standard deviation, t-tests for metric variables, and chi-square tests for nominal variables. For subgroup analyses with less than 30 patients per group, tests for non-normally distributed data were used due to the lower test power.

Results:

RA patients showed significantly lower means of bone density values (minimal T-score, p=0.03) than PsA patients leading to a higher frequency of osteopenic bone densities (p<0.005). However, no differences in the frequency of osteoporotic bone densities could be detected. PsA patients reported a significantly longer disease duration and a higher current GC dosage. In contrast, the frequency of current GC intake was higher in RA patients. Although the calcium intake was higher in the RA group, neither blood levels of calcium and vitamin D, nor the cumulative GC dose (GCCD) or duration of GC therapy could indicate a causal relationship for the differences observed in bone density values between the two groups. The frequency of csDMARD therapy did not differ significantly between PsA and RA patients while the frequency of bDMARD therapy was higher in the PsA group (p=0.04).

Conclusion:

The lower bone density in RA patients seems not to be fully explained by higher GCCD, disease duration or higher levels of inflammation. However, RA patients had a higher frequency of current GC intake. Additionally, differences in bone density between the two groups could be related to the higher number of bDMARD therapies in PsA patients, but further investigations like multivariate analyses with higher numbers of patients are necessary. Furthermore there is more need for research on possible molecular and genetic factors in PsA, which are protecting from low bone density.

Disclosure of Interests:

Desiree Freier: None declared, Edgar Wiebe: None declared, Robert Biesen: None declared, Thomas Buttgereit: None declared, Sandra Hermann: None declared, Timo Gaber: None declared, Frank Buttgereit Grant/research support from: Amgen, BMS, Celgene, Generic Assays, GSK, Hexal, Horizon, Lilly, medac, Mundipharma, Novartis, Pfizer, Roche, and Sanofi.

SAT0450 GLUCOCORTICOID-INDUCED OSTEOPOROSIS IN PATIENTS WITH CHRONIC INFLAMMATORY RHEUMATIC DISEASES: A MULTIVARIATE LINEAR REGRESSION ANALYSIS IDENTIFYING PREDICTIVE FACTORS FOR LOW BONE MASS

Background:

Rheumatic diseases are associated with increased systemic bone loss and fracture risk related to chronic inflammation, disease-specific, general and demographic risk factors as well as treatment with glucocorticoids (GC). Yet, there is evidence that GCs may, by adequately suppressing systemic inflammation, also have a positive effect on bone mineral density (BMD) and fracture risk1.

Objectives:

The purpose of this study was to investigate the prevalence of osteoporosis and fragility fractures in patients with inflammatory rheumatic diseases and to analyze the impact that treatment with GCs, other known risk factors and preventive measures have on bone health in these patients.

Methods:

Rh-GIOP is an ongoing prospective observational study collecting and analyzing disease- and bone-related data from patients with chronic inflammatory rheumatic diseases and psoriasis treated with GCs. In this cross-sectional analysis, we evaluated the initial visit of 1091 patients. A multivariate linear regression model with known or potentially influential factors adjusted for age and sex was used to identify predictors of BMD as measured by dual-energy X-ray absorptiometry (DXA). Multiple imputation was applied for missing baseline covariate data.

Results:

In the total cohort of 1091 patients (75% female of which 87.5% were postmenopausal) with a mean age of 62.1 (±13.2) years, the prevalence of osteoporosis by DXA was 21.7%, while fragility fractures have occurred in 31.2% of the study population (6.7% vertebral, 27.7% non-vertebral). Current GC therapy was common (64.9%), with a median daily dose of 5.0mg [0.0;7.5], a mean life-time total GC dose of 17.7g (±24.6), and a mean GC therapy duration of 7.8 years (±8.5). Bisphosphonates were the most commonly used anti-osteoporotic drug (12.6%).

Multivariate analysis showed that BMD as expressed by the minimum T-Score at all measured sites was negatively associated with higher age, female sex and menopause as well as Denosumab and Bisphosphonate treatment. A positive association with BMD was found for body mass index as well as current and life-time (cumulative) GC dose. While comedication with proton-pump-inhibitors significantly predicted low bone mass, concomitant use of non-steroidal anti-inflammatory drugs showed a positive association with BMD. Of the measured bone-specific laboratory parameters, higher alkaline phosphatase levels were determinants of low DXA-values, while the association was positive for gamma-glutamyltransferase.

BMD was neither predicted by duration of GC treatment nor by treatment with disease modifying anti-rheumatic drugs.

Predictive variables for BMD differed at the respective anatomical site. While treatment with Denosumab predicted low bone mass at the lumbar spine and not at the femoral neck, the opposite was true for health assessment questionnaire (HAQ) score. Current and life-time GC-dose as well as direct sun-exposure of more than 30 minutes daily were positively associated with bone mass at the femoral sites only.

Conclusion:

This cross-sectional analysis of a prospective cohort study quantified the prevalence of osteoporosis and identified predictive variables of BMD in patients with rheumatic diseases.

Multivariate analyses corroborated low BMD to be predicted by traditional factors like age, female sex and menopause but showed current and well as life-time GC dose to be positively associated with BMD in our cohort of patients with chronic inflammatory rheumatic diseases. This suggests that optimal management of disease activity with GCs might be beneficial in order to avoid bone loss due to inflammation.

References:

[1]Güler-Yüksel et al. “Glucocorticoids, Inflammation and Bone.” Calcified Tissue International (January 08 2018).

Disclosure of Interests:

Edgar Wiebe: None declared, Desiree Freier: None declared, Dörte Huscher: None declared, Robert Biesen: None declared, Sandra Hermann: None declared, Frank Buttgereit Grant/research support from: Amgen, BMS, Celgene, Generic Assays, GSK, Hexal, Horizon, Lilly, medac, Mundipharma, Novartis, Pfizer, Roche, and Sanofi.

SAT0372 PATIENTS WITH PSORIATIC ARTHRITIS SHOW HIGHER BONE DENSITY COMPARED TO AGE AND GENDER MATCHED PATIENTS WITH ANKYLOSING SPONDYLITIS

Background:

The prevalence of osteoporosis in inflammatory rheumatic diseases such as psoriatic arthritis (PsA) has not been sufficiently clarified yet, and the data in the literature are heterogeneous. In addition, it is still unclear to what extent patients with PsA differ in terms of bone density from patients with other forms of spondyloarthritis such as ankylosing spondylitis (AS).

Objectives:

In an interim analysis of the Rh-GIOP Study (ClinicalTrials.gov IdentifierNCT02719314), we observed that PsA patients demonstrated more frequently normal bone density than any other patient group analyzed (suffering from e.g. rheumatoid arthritis or systemic sclerosis). The main objective of this investigation was to compare bone density data from patients with PsA and AS, as both diseases belong to the spondyloarthritis group. 1100 patients with inflammatory rheumatic diseases provided the basis of Rh-GIOP, a prospective study monitoring glucocorticoid (GC)-induced osteoporosis in patients with rheumatic diseases. Rh-GIOP was established in 2015 at the Charité University Hospital. Bone mineral density data were measured by dual x-ray absorptiometry (DXA).

Methods:

92 patients with PsA (65% female) were compared with 51 patients suffering from AS (35% female). Potential risk and protective factors (e.g. data on GC treatment, anti-rheumatic therapy), laboratory parameters (e.g. Vitamin D, alkaline phosphatase, calcium and inflammatory markers) and functional status (e.g. Health Assessment Questionnaire, sporting activities, back pain) were compared between these groups. Statistical analysis was performed descriptively using mean and standard deviation, t-tests for metric variables, and chi-square tests for nominal variables. Due to the heterogeneous gender distribution, an additional statistical matching was performed to compare patients matched by age and gender.

Results:

Patients with PsA displayed significantly higher minimal T-scores than patients with AS (p=0.003) even though patients with AS were younger and more often male (p<0.001). AS patients showed a higher frequency of osteopenic bone densities (p<0.05), however, no differences in the frequency of osteoporotic bone densities were found. Body-mass-index (BMI) was significantly higher (p<0.001) in PsA patients. PsA patients demonstrated a higher frequency of csDMARD use (p<0.001). Additional analyses among PsA patients with and without csDMARDs revealed also significantly higher minimal T-scores in PsA patients taking csDMARDs (90% Methotrexate), and both groups showed the same average of age and gender distribution. Furthermore, AS patients complained significantly more often of back pain (96 % vs. 74%, p=0.001) than PsA patients. No differences in GC use or cumulative GC dose were found. All results could be confirmed when groups were matched by age and gender.

Conclusion:

Our results demonstrate that patients with PsA display higher bone density compared to age and gender matched patients with ankylosing spondylitis. Possible influencing factors could be the higher frequency of csDMARD use, higher BMI or the lower frequency of back pain in PsA patients. Multivariate tests and additional biomarker investigations in larger cohorts are necessary to corroborate these findings and to identify underlying pathogenic differences which could serve for an explanation.

Disclosure of Interests:

Desiree Freier: None declared, Edgar Wiebe: None declared, Robert Biesen: None declared, Thomas Buttgereit: None declared, Sandra Hermann: None declared, Timo Gaber: None declared, Frank Buttgereit Grant/research support from: Amgen, BMS, Celgene, Generic Assays, GSK, Hexal, Horizon, Lilly, medac, Mundipharma, Novartis, Pfizer, Roche, and Sanofi.

Autoantibodies, complement and type I interferon as biomarkers for personalized medicine in SLE

Systemic lupus erythematosus (SLE) can be a mysterious disease, presenting with extremely divergent clinical phenotypes. Already, biomarkers are very helpful tools for diagnosis, assessment and monitoring of disease activity, differential diagnosis of clinical manifestations, prediction of the disease course and stratified therapy, and they hold the key to personalized medicine in SLE. We summarize the clinical information that can only be supplied by autoantibodies, complement components and interferon biomarkers in this diverse disease.

Serum antibodies to human leucocyte antigen (HLA)-E, HLA-F and HLA-G in patients with systemic lupus erythematosus (SLE) during disease flares: Clinical relevance of HLA-F autoantibodies

T lymphocyte hyperactivity and progressive inflammation in systemic lupus erythematosus (SLE) patients results in over-expression of human leucocyte antigen (HLA)-Ib on the surface of lymphocytes. These are shed into the circulation upon inflammation, and may augment production of antibodies promoting pathogenicity of the disease. The objective was to evaluate the association of HLA-Ib (HLA-E, HLA-F and HLA-G) antibodies to the disease activity of SLE. The immunoglobulin (Ig)G/IgM reactivity to HLA-Ib and β2m in the sera of 69 German, 29 Mexican female SLE patients and 17 German female controls was measured by multiplex Luminex(®)-based flow cytometry. The values were expressed as mean flourescence intensity (MFI). Only the German SLE cohort was analysed in relation to the clinical disease activity. In the controls, anti-HLA-G IgG predominated over other HLA-Ib antibodies, whereas SLE patients had a preponderance of anti-HLA-F IgG over the other HLA-Ib antibodies. The disease activity index, Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)-2000, was reflected only in the levels of anti-HLA-F IgG. Anti-HLA-F IgG with MFI level of 500-1999 was associated with active SLE, whereas inactive SLE revealed higher MFI (>2000). When anti-HLA-F IgG were cross-reactive with other HLA-Ib alleles, their reactivity was reflected in the levels of anti-HLA-E and -G IgG. The prevalence of HLA-F-monospecific antibodies in SLE patients was also associated with the clinical disease activity. Anti-HLA-F IgG is possibly involved in the clearance of HLA-F shed from lymphocytes and inflamed tissues to lessen the disease's severity, and thus emerges as a beneficial immune biomarker. Therefore, anti-HLA-Ib IgG should be considered as a biomarker in standard SLE diagnostics.

[DNA microarrays]

Since their development in the 1990s DNA microarrays have advanced to one of the most important technologies for biomedical research. Miniaturization enables up to 1 million different sequence-specific DNA hybridization tests to be performed on an area of less than 2 cm². Depending on the selection of oligonucleotide sequences, which are assembled on a microarray and on the treatment of samples prior to hybridization, up to genome-wide analyses for genotypes, gene expression, epigenetic changes or promoter activation can be performed. Increasing knowledge about the human genome advances commercial pre-assembly of DNA microarrays with selected oligonucleotide sequences for specialized applications. In clinical rheumatology gene expression analyses in treatment studies are of increasing importance. Similarly, this technique also identified new biomarkers that allow even better assessment of the current disease activity. The varieties of application enable the possibility of systematic research on the immunological response to specific patterns after stimulation. This opens up opportunities to detect and differentiate immunological reaction patterns better.

[Systemic lupus erythematosus. Target criteria for treatment]

Systemic lupus erythematosus (SLE) is a chronic systemic intermittent autoimmune disease, which can affect nearly all organ systems. The disease is characterized by the detection of more than 100 different auto-antibodies. For the clinical practice as well as in controlled clinical studies it is absolutely necessary to define target criteria which allow the evaluation of the effectiveness of therapy. Many instruments are available for measuring the activity of the disease, the quality of life, the extent of irreversible damage and the individual manifestation in organs. There are also now various biomarkers to characterize the pathophysiologic aspects, clinical activity, therapeutic effectiveness and prognosis.