POS0515 THE ASSOCIATION BETWEEN AUTOANTIBODIES AND RISK FOR VENOUS THROMBOEMBOLIC EVENTS AMONG PATIENTS WITH RHEUMATOID ARTHRITIS

Background

Patients with rheumatoid arthritis (RA) have an increased risk for cardiovascular disease, including venous thromboembolic events (VTE)1. The reason behind the increased VTE risk is incompletely understood, but inherent features of RA, such as RA specific autoantibodies, could potentially play a role. For example, studies have linked occurrence and levels of rheumatoid factor (RF) in the general population to increased VTE risk2. We and others have demonstrated an association between ACPA and risk of later ischemic cardiovascular events3. There are also potential mechanistic links; citrullinated fibrinogen (cFib) has been associated to clot stability4.

Objectives

We aimed to examine the association between anti-modified protein antibodies (AMPAs) and risk of VTE in RA.

Methods

We included 2809 individuals newly diagnosed with RA and included in the Swedish EIRA study 1996-2009. Through linkage to nationwide health care registers we identified past and incident events of VTE based on validated ICD code algorithms. We centrally typed baseline sera for anti-CCP2, 20 different ACPA sub-specificities, RF isotypes, carbamylated antibodies and 10 additional post-translational modifications. We followed all individuals from RA diagnosis up until their first ever VTE event, migration, death or end of study (2020-12-31) whichever occurred first. We used a Cox regression to estimate hazard ratios (HR) with 95% confidence intervals (CI). Individuals with a history of a VTE event (n=27) at RA diagnosis were excluded.

Results

We included 2782 individuals; 72% were women, median age at RA diagnosis was 54 years (inter quartile range (IQR) 18 years) and median follow-up time was 15.5 (IQR 6.8) years. During follow-up 177 incident VTE events were observed corresponding to an incidence of 5.0 per 1,000 person years.

1797 (64.6%) patients were positive for IgG anti-CCP2 and the HR for VTE (vs. being negative for anti-CCP2) was 1.33 (95%CI 1.00-1.78). The risk of VTE increased with the level of anti-CCP2, with an HR of 1.49 (95%CI 0.99-2.22) for the group with extreme levels compared to those negative for anti-CCP2 (p-value for trend 0.048). For IgA anti-CCP2 the HR was 1.35 (95% CI 0.99-1.84) when comparing those expressing IgA anti-CCP2 against those who did not.

Of 20 ACPA fine-specificities studied, 18 occurred with a frequency > 10% in our sample. The median number of fine-specificities expressed was 6 (IQR 11). The risk of VTE increased with the number of ACPA fine-specificities expressed (p-value for trend 0.033). At the 0.05 significance level, two fine-specificities were each associated with VTE; cPept Z1 [HR=1.40 (95%CI 1.06-84)] and cPept-1 [HR=1.47 (95%CI 1.12-1.93)]. None of the six antibodies against cFib assessed were statistically significantly associated with VTE risk. No associations were observed for other AMPAs. Among the three RF isotypes, only IgM RF was statistically associated with VTE [HR=1.38 (95%CI 1.04-1.83)].

Conclusion

RA-related antibodies analysed in clinical practice (anti-CCP2 IgG, RF) are associated not only with risk of myocardial infarction, stroke and cardiovascular death as previously demonstrated but also with VTE. There were no clear specific signals with ACPA fine-specificities, other AMPAs, or IgA RA autoantibodies.

References

[1]Holmqvist ME,et al. Risk of venous thromboembolism in patients with rheumatoid arthritis and association with disease duration and hospitalization. JAMA. 2012;308(13):1350-6.

[2]Meyer-Olesen CL, et al. Increased rheumatoid factor and deep venous thrombosis: 2 cohort studies of 54628 individuals from the general population. Clin Chem. 2015;61(2):349-59.

[3]Westerlind H, et al. Anti-citrullinated protein antibody specificities, rheumatoid factor isotypes and incident cardiovascular events in patients with rheumatoid arthritis. Arthritis Rheumatol. 2020.

[4]Maners J, et al. A Mendelian randomization of gamma’ and total fibrinogen levels in relation to venous thromboembolism and ischemic stroke. Blood. 2020;136(26):3062-9.

Disclosure of Interests

Helga Westerlind: None declared, Alf Kastbom: None declared, Johan Rönnelid: None declared, Monika Hansson: None declared, Lars Alfredsson: None declared, Linda Mathsson-Alm Employee of: LMA an employee of Thermo Fisher Scientific producing the ACPA sub-specificity test, Guy Serre: None declared, Martin Cornillet: None declared, Rikard Holmdahl Consultant of: historically several. Currently paid advisor for Lipum AB and Cyxone AB, Per-Johan Jakobsson Consultant of: UCB – Nov 2021 to Feb 2022., Karl Skriner: None declared, Holger Bang Employee of: HB is an employee of Orgentec Diagnostica, an IVRc company, Lars Klareskog: None declared, Saedis Saevarsdottir Employee of: SS is a part-time employee of deCODE genetics Inc., Karin Lundberg: None declared, Caroline Grönwall: None declared, Johan Askling Grant/research support from: AbbVie, AstraZeneca, Bristol Myers Squibb, Eli Lilly, Janssen, Merck, Pfizer, Roche, Samsung Bioepis, Sanofi, and UCB.

POS0009 THE RELATIONSHIP BETWEEN DIFFERENT IGG AND IGA ANTI-MODIFIED PROTEIN AUTOANTIBODIES IN RHEUMATOID ARTHRITIS

Background:

Seropositive rheumatoid arthritis (RA) is characterized by the presence of rheumatoid factor (RF) and anti-citrullinated protein autoantibodies (ACPA) with different fine-specificities. Yet, other serum anti-modified protein autoantibodies (AMPA), e.g. anti-carbamylated (Carb), anti-acetylated (KAc), and anti-malondialdehyde acetaldehyde (MAA) modified protein antibodies, have been described. By using RA patient single-cell derived monoclonal antibodies we have previously shown that individual ACPA clones recognize small distinct citrulline-containing epitopes giving them extensive multireactivity when these epitopes are found in many peptides and proteins. Moreover, certain CCP2+ multireactive ACPA clones bind also to cabamylated and acetylated autoantigens [1].

Objectives:

To provide a comprehensive evaluation of serum IgG and IgA autoreactivity to different post-translational modifications in RA.

Methods:

We analyzed 30 different IgG and IgA AMPA reactivities to modified antigens by ELISA and autoantigen arrays, in N=1985 newly diagnosed RA patients and population controls. The study utilized both previously established (i.e IgG and IgA CCP2; IgG ACPA fine-specificities; IgG anti-Carb fibrinogen and Carb FCS; IgG and IgA Cit/Carb/KAc/Orn(Ac)-vimentin), and novel assays (e.g. IgG anti-MAA and IgG anti-acetylated histones). Association with patient characteristics such as smoking and disease activity were explored. The newly developed assays were also evaluated in SLE disease controls and CCP2+ RA-risk individuals without arthritis.

Results:

Carb and KAc reactivities by different assays were primarily seen in patients also positive for citrulline-reactivity. Modified vimentin (mod-Vim) peptides were used for direct comparison of different AMPA reactivities, revealing that IgA AMPA recognizing mod-Vim was mainly detected in subsets of patients with high IgG anti-Cit-Vim levels and a history of smoking. IgG acetylation reactivity was mainly detected in a subset of patients with Cit and Carb reactivity. Anti-acetylated histone 2B reactivity was RA-specific and associated with high anti-CCP2 IgG levels, multiple ACPA fine-specificities, and smoking. This reactivity was also found to be present in CCP2+ RA-risk individuals without arthritis. Our data further demonstrate that IgG autoreactivity to MAA was increased in RA compared to controls with highest levels in CCP2+ RA, but was not RA-specific, and showed low correlation with other AMPA. Anti-MAA was instead associated with disease activity and was not significantly increased in CCP2+ individuals at risk of RA. Notably, RA patients could be subdivided into four different subsets based on their AMPA IgG and IgA reactivity profiles.

Conclusion:

We conclude that autoantibodies exhibiting different patterns of ACPA fine-specificities as well as Carb and KAc reactivity are present in RA and may be derived from multireactive B-cell clones. Anti-Carb and anti-KAc could be considered reactivities within the “Cit-umbrella” similar to ACPA fine-specificities, while MAA is distinctly different.

References:

[1]Sahlström P, Hansson M, Steen J, Amara K, Titcombe PJ, Forsström B, Stålesen R, Israelsson L, Piccoli L, Lundberg K, Klareskog L, Mueller DL, Catrina AI, Skriner K, Malmström V, Grönwall C. Different Hierarchies of Anti-Modified Protein Autoantibody Reactivities in Rheumatoid Arthritis. Arthritis Rheumatol. 2020 Oct;72(10):1643-1657. PMID: 32501655

Caroline Grönwall: None declared, Lisa Liljefors: None declared, Holger Bang Employee of: Employee at ORGENTEC Diagnostika GmbH, Aase Hensvold: None declared, Monika Hansson: None declared, Linda Mathsson-Alm Employee of: Employee at Thermo Fisher Scientific, Lena Israelsson: None declared, Anna Svärd: None declared, Cyril CLAVEL: None declared, Elisabet Svenungsson: None declared, Iva Gunnarsson: None declared, Guy Serre: None declared, Saedis Saevarsdottir: None declared, Alf Kastbom: None declared, Lars Alfredsson: None declared, Vivianne Malmström: None declared, Johan Rönnelid: None declared, Anca Catrina: None declared, Karin Lundberg: None declared, Lars Klareskog: None declared

POS1425 ANTIBODIES TO PORPHYROMONAS GINGIVALIS ASSOCIATE WITH THE PRESENCE OF RHEUMATOID ARTHRITIS-RELATED AUTOANTIBODIES IN PATIENTS WITH PERIODONTITIS

Background:

Epidemiologic studies have demonstrated a link between periodontitis (PD) and rheumatoid arthritis (RA), specifically RA characterized by anti-citrullinated protein antibodies (ACPA). The keystone pathogen driving PD, Porphyromonas gingivalis (Pg), is the only pathogen known to express peptidylarginine deiminase (PAD), a citrullinating enzyme. Hence, Pg has been proposed to be involved in triggering the ACPA response, by generating citrullinated antigens in an inflammatory milieu(1). Another major virulence factor of Pg is arginine gingipain B (RgpB), a proteinase which cleaves proteins so that P.PAD can access the site where citrullination takes place. We have previously shown elevated anti-RgpB IgG levels in ACPA+ RA patients, even before clinical onset(2, 3), and we hypothesize that anti-RgpB IgG could serve as a serological marker to identify PD patients with increased risk of developing ACPA+ RA.

Objectives:

Based on this hypothesis, we set out to investigate whether anti-RgpB IgG was associated with PD, PD severity, autoimmunity in general, and the ACPA response in particular.

Methods:

Anti-RgpB IgG, as well as RA- and systemic lupus erythematosus (SLE)-related autoantibodies targeting cyclic citrullinated peptide(s) (CCP2), rheumatoid factor (RF), dsDNA, cardiolipin, and β2 glycoprotein, were measured by ELISA in serum samples from the ParoKrank study, which is a well-characterized cohort of 805 patients with a first myocardial infarction and 805 matched controls, where periodontal status has been determined by dentists(4). In this study, individuals with PD (n=941) were compared to individuals without PD (n=557).

Results:

We detected significantly elevated (p<0,0001) anti-RgpB IgG levels in PD compared to non-PD individuals, with highest levels recorded in severe PD. Anti-RgpB IgG levels were significantly increased in PD patients positive for CCP2 and/or RF (n=50), when compared to PD patients negative for CCP2 and RF (n=507), p<0,05, and when compared to non-PD individuals positive for CCP2 and/or RF (n=62), p < 0,05. Notably, these differences were not seen for SLE-related autoantibodies. In addition, anti-RgpB IgG levels were significantly elevated amongst MI patients versus controls (p < 0,05), supporting the previous finding that PD is more common among MI patients(4).

Conclusion:

Our data demonstrates a specific association between severe PD, elevated anti-RgpB IgG levels and RA-related autoantibodies, supporting a role for Pg in linking PD to ACPA+ RA. Further investigation will be needed to confirm whether anti-RgpB IgG can be used as a serological marker to identify PD patients with increased risk of developing ACPA+ RA.

References:

[1]Rosenstein ED, Greenwald RA, Kushner LJ, Weissmann G. Hypothesis: the humoral immune response to oral bacteria provides a stimulus for the development of rheumatoid arthritis. Inflammation. 2004;28(6):311-8.

[2]Kharlamova N, Jiang X, Sherina N, Potempa B, Israelsson L, Quirke AM, et al. Antibodies to Porphyromonas gingivalis Indicate Interaction Between Oral Infection, Smoking, and Risk Genes in Rheumatoid Arthritis Etiology. Arthritis Rheumatol. 2016;68(3):604-13.

[3]Johansson L, Sherina N, Kharlamova N, Potempa B, Larsson B, Israelsson L, et al. Concentration of antibodies against Porphyromonas gingivalis is increased before the onset of symptoms of rheumatoid arthritis. Arthritis Res Ther. 2016;18(1):201.

[4]Rydén L, Buhlin K, Ekstrand E, Faire Ud, Gustafsson A, Holmer J, et al. Periodontitis Increases the Risk of a First Myocardial Infarction. Circulation. 2016;133(6):576-83.

Disclosure of Interests:

None declared

Retinal vascular diameters in relation to physical activity in Danish children - The CHAMPS Eye Study

Our objective was to determine associations between retinal vascular caliber and physical activity (PA) in a school-based child cohort. In a prospective study, we created a childhood cumulative average PA-index using objectively measured PA (accelerometry) assessed at four periods between 2009 and 2015. Cumulative exposure to PA intensities was estimated. Cross-sectional examinations on biomarkers, anthropometry, and ophthalmological data including retinal fundus photographs were performed in 2015. Semi-automated measurements of retinal vascular diameters were performed and summarized into central retinal arteriolar and venular equivalents (CRAE, CRVE). We included 307 participants. Mean age in 2015 was 15.4 years (0.7). The mean CRAE and CRVE were 156.5 μm (2.8) and 217.6 μm (7.7), respectively. After adjusting for age, gender, and axial length, more time in PA was independently related to thinner retinal venules (β-coefficient = -1.25 μm/%, 95% confidence interval = -2.20, -0.30, P < .01). Sedentary time was associated with wider venules (P < .01). Furthermore, birthweight (β-coefficient = 0.56 μm/%, 95% confidence interval = 0.18, 0.95, P < .01) was associated with CRVE. Blood pressure was associated with thinner retinal arterioles (β-coefficient = -0.19 μm/mmHg, 95% confidence interval = -0.36, -0.01, P = .04). We concluded that children with higher PA in childhood had thinner retinal venular caliber. Our results suggest that PA during childhood positively impacts the retinal microcirculation and that retinal vascular analysis may be a possible assessment to detect microvascular impairments in children with an increased risk of future cardiovascular disease.

Murine polyomavirus virus-like particles carrying full-length human PSA protect BALB/c mice from outgrowth of a PSA expressing tumor

Virus-like particles (VLPs) consist of capsid proteins from viruses and have been shown to be usable as carriers of protein and peptide antigens for immune therapy. In this study, we have produced and assayed murine polyomavirus (MPyV) VLPs carrying the entire human Prostate Specific Antigen (PSA) (PSA-MPyVLPs) for their potential use for immune therapy in a mouse model system. BALB/c mice immunized with PSA-MPyVLPs were only marginally protected against outgrowth of a PSA-expressing tumor. To improve protection, PSA-MPyVLPs were co-injected with adjuvant CpG, either alone or loaded onto murine dendritic cells (DCs). Immunization with PSA-MPyVLPs loaded onto DCs in the presence of CpG was shown to efficiently protect mice from tumor outgrowth. In addition, cellular and humoral immune responses after immunization were examined. PSA-specific CD4⁺ and CD8⁺ cells were demonstrated, but no PSA-specific IgG antibodies. Vaccination with DCs loaded with PSA-MPyVLPs induced an eight-fold lower titre of anti-VLP antibodies than vaccination with PSA-MPyVLPs alone. In conclusion, immunization of BALB/c mice with PSA-MPyVLPs, loaded onto DCs and co-injected with CpG, induces an efficient PSA-specific tumor protective immune response, including both CD4⁺ and CD8⁺ cells with a low induction of anti-VLP antibodies.

Tumor-specific bacteriophages induce tumor destruction through activation of tumor-associated macrophages

We recently reported that administration of tumor-specific bacteriophages initiates infiltration of neutrophilic granulocytes with subsequent regression of established B16 tumors. The aim of the current study was to investigate the mechanism of action of bacteriophage-induced tumor regression and to examine possible stimulatory effects of bacteriophages on macrophages. We observed that the mechanism of phage-induced tumor regression is TLR dependent as no signs of tumor destruction or neutrophil infiltration were observed in tumors in MyD88(-/-) mice in which TLR signaling is abolished. The microenvironment of bacteriophage-treated tumors was further analyzed by gene profiling through applying a low-density array preferentially designed to detect genes expressed by activated APCs, which demonstrated that the M2-polarized tumor microenvironment switched to a more M1-polarized milieu following phage treatment. Bacteriophage stimulation induced secretion of proinflammatory cytokines in both normal mouse macrophages and tumor-associated macrophages (TAMs) and increased expression of molecules involved in Ag presentation and costimulation. Furthermore, mouse neutrophils selectively migrated toward mediators secreted by bacteriophage-stimulated TAMs. Under these conditions, the neutrophils also exhibited increased cytotoxicity toward B16 mouse melanoma target cells. These results describe a close interplay of the innate immune system in which bacteriophages, located to the tumor microenvironment due to their specificity, stimulate TAMs to secrete factors that promote recruitment of neutrophils and potentiate neutrophil-mediated tumor destruction.

Multiple antibody reactivities to citrullinated antigens in sera from patients with rheumatoid arthritis: association with HLA-DRB1 alleles

BACKGROUND

Autoantibodies to cyclic citrullinated peptides (anti-CCP) are present in most patients with rheumatoid arthritis (RA), and associate with HLA-DRB1 shared epitope (SE) alleles.

OBJECTIVE

To investigate reactivities of anti-CCP to various citrullinated proteins/peptides, which represent potential autoantigens in RA, and to examine the relationship between such antibodies, and their association with genetic variants within HLA-DRB1 SE alleles.

METHODS

Serum samples from 291 patients with established RA and 100 sex- and age-matched healthy subjects were included in this study. Sera were first analysed for presence of anti-CCP antibodies and further for IgG and IgA antibodies towards candidate autoantigens in both their native and citrullinated form including: fibrinogen, alpha-enolase peptide-1 and the C1-epitope of type II collagen (C1(III)). Antibody specificity was confirmed by cross-reactivity tests. HLA-DR genotyping was performed.

RESULTS

72% of patients with RA were anti-CCP positive. Among the candidate autoantigens examined, IgG antibodies to citrullinated fibrinogen were found in 66% of patients' sera and in 41% for both citrullinated alpha-enolase peptide-1 and citrullinated C1(III). These antibodies were mainly seen in the anti-CCP-positive patient group; they were specific for their respective antigen and displayed limited cross reactivity. IgA responses were also detected, but less frequently than IgG. Anti-CCP and anti-citrullinated protein antibodies were associated with HLA-DRB1*04 rather than with HLA-DRB1*01 alleles.

CONCLUSIONS

Antibodies directed against several citrullinated antigens are present in CCP-positive RA, with many patients displaying multireactivity. All specific reactivities were primarily associated with the HLA-DRB1*04 alleles, suggesting common pathways of anti-citrulline immunity.

Citrullinated Proteins in Arthritis; their Presence in Joints and Effects on Immunogenicity

Autoantibodies directed against citrulline‐containing proteins have an impressive specificity of nearly 100% in RA patients and a suggestive involvement in the pathogenesis. The targeted epitopes are generated by a post‐translational modification catalysed by the calcium‐dependent enzyme peptidyl arginine deaminase that converts the positively charged arginine to polar but uncharged citrullin. The aim of this study was to analyse the presence of citrulline in the joints at different time points of collagen‐induced arthritis in DA rats by immunohistochemistry and to investigate how immunogenicity and arthritogenicity was affected by citrullination of rat serum albumin (RSA) and collagen type II (CII). Our results indicate that citrulline could be detected in joints of arthritic animals, first appearance at the onset of disease and increasing as disease progressed into a chronic state. Unimmunized animals or time points before clinical signs of arthritis were negative. By morphology, we state that some infiltrating macrophages as well as the cartilage surface stain positive for citrulline, while the major source of citrullinated proteins appears to be fibrin depositions. A specific Cit‐RSA T‐cell response was observed in animals challenged by citrullinated RSA, no response was recorded when RSA was used as a stimulus. The IgG analysis reveals not only a response towards the modified protein but also cross‐reactivity to native RSA. No T‐cell or B‐cell response was noted in animals injected with unmodified RSA. Cit‐CII induced a disease with higher incidence and earlier onset than did the native counterpart. We conclude that, in contrast to the human disease, citrulline does not seem to appear before clinical signs. As inflammation proceeds, citrulline is detected specifically in the joints. All other organs investigated were negative. We also conclude that citrullination of a protein can break tolerance and increase its arthritogenic properties.

CD4+CD25high T cells are enriched in the tumor and peripheral blood of prostate cancer patients

In this study, we investigated whether CD4+CD25high regulatory T cells (Treg) are increased in the tumor tissue and peripheral blood of early-stage prostate cancer patients undergoing prostatectomy. We show that the prevalence of CD4+CD25high T cells inside the prostate was significantly higher in the tumor compared with benign tissue from the same prostate. Furthermore, the frequency of CD4+CD25high T cells in peripheral blood was significantly higher in prostate cancer patients compared with normal donors. A proportion of the CD4+CD25high T cells was also shown to be glucocorticoid-induced TNF receptor, ICOS, and FOXP3 positive. Moreover, CD4+CD25+ T cells from blood and supernatants from cultured prostate tumor tissue samples exhibited immunosuppressive function in vitro. Furthermore, supernatants from cultured prostate tissue samples and prostate cancer ascites fluid induced migration of CD4+CD25+ T cells and were shown to contain the regulatory T cell chemokine CCL22 by ELISA. Our findings indicate that Tregs are an important cellular component of early-stage prostate tumors, and thus new therapeutic strategies aimed at inhibition or depletion of Tregs may improve prostate cancer immunotherapy.

CD4+CD25high T cells are enriched in the tumor and peripheral blood of prostate cancer patients

In this study, we investigated whether CD4+CD25high regulatory T cells (Treg) are increased in the tumor tissue and peripheral blood of early-stage prostate cancer patients undergoing prostatectomy. We show that the prevalence of CD4+CD25high T cells inside the prostate was significantly higher in the tumor compared with benign tissue from the same prostate. Furthermore, the frequency of CD4+CD25high T cells in peripheral blood was significantly higher in prostate cancer patients compared with normal donors. A proportion of the CD4+CD25high T cells was also shown to be glucocorticoid-induced TNF receptor, ICOS, and FOXP3 positive. Moreover, CD4+CD25+ T cells from blood and supernatants from cultured prostate tumor tissue samples exhibited immunosuppressive function in vitro. Furthermore, supernatants from cultured prostate tissue samples and prostate cancer ascites fluid induced migration of CD4+CD25+ T cells and were shown to contain the regulatory T cell chemokine CCL22 by ELISA. Our findings indicate that Tregs are an important cellular component of early-stage prostate tumors, and thus new therapeutic strategies aimed at inhibition or depletion of Tregs may improve prostate cancer immunotherapy.