Autoantibodies against C5aR1, C3aR1, CXCR3, and CXCR4 are decreased in primary Sjogren's syndrome

BACKGROUND

Networks formed of numerous autoantibodies (aabs) directed against G-protein coupled receptors (GPCR) have been suggested to play important role in autoimmune disorders. In present study, we aimed to evaluate the association between anti-GPCR antibodies and primary Sjogren's syndrome (pSS) to determine the potential pathogenic factors.

METHODS

By applying a cell membrane-based ELISA technique, which is capable of detecting aabs against conformational epitopes within GPCR, serum levels of fourteen GPCR were determined in well-characterized patients with pSS (n = 52) and gender-matched healthy controls (n = 54). Comparisons between groups were analyzed by two-tailed Mann-Whitney U test, Bonferroni correction was applied for multiple comparisons. Spearman`s rank correlation coefficients were calculated between variables and visualized by heat map.

RESULTS

Compared to healthy subjects, sera of patients with pSS showed significantly higher binding to β2AR and ETAR, but lower binding to C5aR1, C3aR1, CXCR3, and CXCR4. Autoantibodies against C5aR1, C3aR1, CXCR3, and CXCR4 were also decreased in patients with rheumatoid arthritis. In pSS patients, levels of anti-CXCR3 and anti-CXCR4 antibodies were negatively correlated with circulating lymphocyte counts. Furthermore, correlation signatures of anti-GPCR antibodies changed dramatically in the patients with pulmonary involvement.

CONCLUSIONS

This study demonstrates an association between pSS and autoantibodies recognizing GPCR, especially those functionally involved in immune cell migration and exocrine glandular secretion.

Economic evaluation of adverse events of dabrafenib plus trametinib versus nivolumab in patients with advanced BRAF-mutant cutaneous melanoma for adjuvant therapy in Germany

Background: Adjuvant treatment options have become the standard therapy for stage III and IV resectable cutaneous melanoma. Two recent studies led to the registration of dabrafenib and trametinib as targeted therapies for BRAF-mutated melanoma, and of immunotherapy with nivolumab irrespective of BRAF-mutation status. Both therapies have different spectrums of adverse events. Objective: To estimate the financial impact of side effects from the perspective of the German statutory sick funds to compare both therapeutic options and to relate the burden to the overall costs of the treatment.

STUDY DESIGN AND SETTING

Thirty-six adverse event categories for the combination of dabrafenib and trametinib ('combi treatment') and for nivolumab were extracted from the original publications of the studies named COMBI-AD and CheckMate 238.

PATIENTS AND INTERVENTION

For all event categories a diagnosis and therapy recommendation were determined according to current national or international guidelines or from leading German textbooks.

MAIN OUTCOME MEASURE

The resulting diagnostic steps, treatments, and therapies were evaluated with unit costs based on the German fee schedule for ambulatory physicians, the German G-DRG scheme, and the German drug price list.

RESULTS

The number of events with nivolumab per one hundred treatments amounted to 3.8 mandatory hospitalizations, 3.5 emergency care events and 0.8 life-threatening events. For the combi treatment, the respective number of events per one hundred treatments was 2.7, 1.8, and 0.5. The overall cost burden was calculated as €899 for nivolumab and €861 for combi-treatment.

CONCLUSION

The treatment of adverse events resulting from adjuvant melanoma therapy showed comparable costs for both therapies.

Safety, efficacy and quality of life of the novel vaginal contraceptive ring containing etonogestrel/ethinylestradiol 11.0/3.474 mg after 3 years of "real life" experience

Combined contraceptive vaginal rings (CVR) are increasingly appreciated due to several beneficial properties like avoidance of the hepatic first-pass effect, a comparatively low dosage of hormones and comfortable use. A further development of the widely used CVR releasing 0.12 mg etonogestrel (ETO) and 0.015 mg ethinylestradiol (EE) per 24 hours has been marketed since 2017. The 11.00/3.474 mg ETO/EE CVR Ornibel® is bioequivalent to the former product but differs in its polymer composition leading to improved stability. Here, results from recent studies on the novel CVR Ornibel® are reviewed including clinical trials on bleeding profile, acceptability, sexual function and other quality of life (QoL) parameters as well as in vitro studies on microbial adhesion to the CVR and the influence of ring rupture on hormone release. Findings are complemented with new data on contraceptive efficacy and safety of the new CVR that were assessed during 3 years of real-life experience.

Thermal conductivity analysis of a new sub-micron sized polystyrene foam

New polystyrene (PS) foams with submicron pore sizes and open pore structure are introduced as potential cores for vacuum insulation panels (VIPs). Measurements of the thermal conductivity λ of the air-filled and evacuated PS foams, the influence of temperature T, opacifiers as well as gas pressure p on the thermal conductivity λ are presented. First results of the foam microstructures, as visualized by electron microscopy, confirm that pore sizes below 1 µm can be achieved. Thermal conductivity values of advanced samples in vacuum of about 7 mW/(m·K) were measured.

May an adrenal incidentaloma change its nature?

BACKGROUND

Up to 70% of adrenal masses detected in patients affected by extra-adrenal malignancy are metastatic lesions. Therefore, detection of an adrenal mass in patients with active or previous malignancy requires a careful differential diagnostic workup. ¹⁸F-Fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) is increasingly being used to determine the malignant potential of adrenal lesions.

CLINICAL CASE

We report the case of a 64-year-old man who had a single adrenal metastasis due to non-small-cell lung carcinoma developing on a pre-existing benign adrenal lesion. This metastasis occurred in a phase of perceived oncological remission and was detected thanks to ¹⁸F-FDG-PET/CT showing a focal adrenal uptake. Contrast-enhanced computed tomography (CT), performed as part of oncological follow-up, and MRI with chemical shift sequences did not lead to the correct diagnosis. The patient underwent laparoscopic adrenalectomy and the pathological evaluation confirmed a lung carcinoma metastasis.

CONCLUSION

The present case highlights the peculiarity of the follow-up of adrenal masses in cancer patients and the primary role of ¹⁸F-FDG-PET/CT in the management of such patients.

Diagnostics and therapy of bilateral choanal atresia in association with CHARGE syndrome

BACKGROUND

Bilateral choanal atresia in patients with CHARGE syndrome becomes symptomatic immediately after birth. A prompt diagnosis, the implementation of sufficient preliminary measures, and the delivery of surgical therapy are crucial. This article is intended to assist in terms of diagnostics and a therapy recommendation.

METHODS

We performed a retrospective study using the medical records of all newborns in the University Hospital in Bonn, diagnosed with bilateral choanal atresia and CHARGE syndrome and underwent surgery at the Department of Otorhinolaryngology, Head and Neck Surgery.

RESULTS

A total of 21 patients have been treated with a unilateral or bilateral choanal atresia. 14 patients were primarily treated with transnasal endoscopy or underwent transnasal endoscopic surgery as a follow-up intervention (73.68%). Nine patients had a syndromal appearance, which was considered a definite diagnosis in six patients (five with CHARGE syndrome). All five patients with CHARGE syndrome received transnasal endoscopic treatment and a stent was inserted.

DISCUSSION

Bilateral choanal atresia can be a life-threatening situation requiring acute measures. The therapeutic trend goes towards transnasal endoscopic resection. Primary intervention should be: minimally invasive, one-stage surgery, functional, and associated with low complication rates. Patency can be increased by saline irrigations, topical corticosteroids, endoscopic controls, and regular dilatation. The insertion of stents is controversially discussed but can be useful in syndromal patients. However, adjuvant therapy with a stent and mitomycin C is increasingly being abandoned. A significantly higher recurrence rate must be expected in association with CHARGE syndrome. Stenting should be considered on an individual basis. Continuous training and support of the parents are obligatory.

Dramatically altered environmental lighting conditions in women with high-risk pregnancy during hospitalization

The maternal circadian time structure is incredibly important in the entrainment and programing of the fetal and newborn circadian time structure. Natural sunlight is the primary environmental time cue for entrainment of circadian rhythms, but high-risk pregnant women spend most of their time indoors with artificial light sources and extremely low levels of natural light both during the day and night. Because the daily level, timing, duration of light exposure and its spectral properties are important in maintaining the normal circadian physiology in humans, we aimed to evaluate the environmental lighting conditions in high-risk pregnant women admitted to hospital for long-term stay. About 30 patients were included in the study. Exposed illuminance, color temperature and effective circadian radiation dose were measured and recorded every 10 s by light dosimeters attached to the patients' clothing. We documented the illuminance of 29 pregnant women on 235 inpatient days. Median (IQR) measured illuminance was 70 (28-173) lux in the morning, 124 (63-241) lux in the afternoon, 19 (6-53) lux in the evening and 0 (0-0) lux at the night. Median illuminance for the 235 inpatient days of assessment was below the recommended EU standard of 100 lux-60.5% of the mornings and 42.7% of the afternoons. The women confined to indoor locations rarely achieved an illuminances more than 300 lux in the morning and in the afternoon. Compared to women with outdoor mobility, those confined indoors have a significantly lower illuminance and color temperature, both in the morning and in the afternoon. Our study presents the first information about the dramatically altered environmental lighting conditions experienced by high-risk pregnant women during their hospital stay. Their exposure to light while in the hospital is significantly lower than exposure to natural daylight levels and below the recommended EU standard.

Effects of altered photoperiod due to COVID-19 lockdown on pregnant women and their fetuses

Maternal circadian rhythms provide highly important input into the entrainment and programming of fetal and newborn circadian rhythms. The light-dark cycle is an important regulator of the internal biological clock. Even though pregnant women spend a greater part of the day at home during the latter stages of pregnancy, natural light exposure is crucial for the fetus. The current recommended COVID-19 lockdown might dramatically alter normal environmental lighting conditions of pregnant women, resulting in exposure to extremely low levels of natural daylight and high-intensity artificial light sources during both day and night. This article summarizes the potential effects on pregnant woman and their fetuses due to prolonged exposure to altered photoperiod and as consequence altered circadian system, known as chronodisruption, that may result from the COVID-19 lockdown.

FRI0001 NEUTROPHILS IN GRANULOMATOSIS WITH POLYANGIITIS DISPLAY FEATURES OF PYROPTOSIS

Background:

Granulomatosis with polyangiitis (GPA) is characterized by extravascular necrotizing granulomatous inflammation and systemic ANCA – associated (AAV) vasculitis with neutrophils as a key player in the pathogenesis (1). We and others have shown that neutrophil-related cell death mechanisms contribute to chronic inflammatory processes in AAV (2, 3). Recently, another form of inflammatory cell death primarily described in monocytes called pyroptosis was also discovered in neutrophils (4). A cardinal feature of pyroptosis is the activation of the NLRP3 inflammasome, a sensor of different pathogen- and damage-associated molecular patterns (PAMP, DAMP), following caspase-1-mediated processing and secretion of IL-1beta (5).

Objectives:

The aim of this study was to investigate, if neutrophils from GPA patients express pyroptosis-related components NLRP3, active caspase 1 and cleaved IL-1beta.

Methods:

Polymorphonuclear leukocytes (PMN) were isolated from peripheral blood of GPA patients and healthy controls (HC) (n = 10 each). Expression of NLRP3, inactive/active caspase 1 and active IL-1beta was determined by western blot. In addition, peripheral blood mononuclear cells (PBMC) were isolated from GPA and HC. mRNA expression ofnlrp3andil1bwas determined by qPCR. To exclude false-positive results by contamination with monocytes we performed flow cytometry analysis of whole blood samples with markers CD3, CD14, CD15, CD66b and NLRP3.

Results:

PMN from GPA patients showed markedly increased expression of NLRP3, active caspase 1 and active IL-1beta compared to HC. In contrast, there was no difference between GPA and HC on the mRNA level of neithernlrp3noril1bin PBMC. In addition, we confirmed by flow cytometry increased expression of NLRP3 in PMN from GPA, but not in monocytes.

Conclusion:

Here we provide evidence, that neutrophils from GPA undergo pyroptosis, demonstrated by increased NLRP3, active caspase 1 expression as well as IL-1beta processing. Neutrophils are present in high numbers at the site of granulomatous lesions of inflamed tissue in GPA and IL-1beta is increased in GPA sera (2). Therefore, neutrophils represent a potential source of IL-1beta in GPA. Given the fact that GPA-associated features such as massive release of necrosis-related DAMP or microbial agents such asStaphylococcus aureus(6) can activate the NLRP3-inflammasome, we identified here a potential relevant mechanism of neutrophils contributing to chronic inflammation of GPA.

References:

[1]Jennette, J.C., and Falk, R.J. (2014). Pathogenesis of antineutrophil cytoplasmic autoantibody-mediated disease. Nat. Rev. Rheumatol.10, 463–473.

[2]Millet, A., Martin, K.R., Bonnefoy, F., Saas, P., Mocek, J., Alkan, M., Terrier, B.,Kerstein,A., Tamassia, N., Satyanarayanan, S.K., et al. (2015). Proteinase 3 on apoptotic cells disrupts immune silencing in autoimmune vasculitis. J. Clin. Invest. 125, 4107–4121.

[3]Schreiber, A., Rousselle, A., Becker, J.U., von Mässenhausen, A., Linkermann, A., and Kettritz, R. (2017). Necroptosis controls NET generation and mediates complement activation, endothelial damage, and autoimmune vasculitis. Proc. Natl. Acad. Sci. 201708247.

[4]Tourneur, L., and Witko-Sarsat, V. (2019). Inflammasome activation: Neutrophils go their own way. J. Leukoc. Biol.105, 433–436.

[5]Bergsbaken, T., Fink, S.L., and Cookson, B.T. (2009). Pyroptosis: Host cell death and inflammation. Nat. Rev. Microbiol.7, 99–109.

[6]Lamprecht, P.,Kerstein, A., Klapa, S., Schinke, S., Karsten, C.M., Yu, X., Ehlers, M., Epplen, J.T., Holl-Ulrich, K., Wiech, T., et al. (2018). Pathogenetic and Clinical Aspects of Anti-Neutrophil Cytoplasmic Autoantibody-Associated Vasculitides. Front. Immunol.9, 1–10.

Disclosure of Interests:

Anja Kerstein-Staehle: None declared, Nadja Leinung: None declared, Jannik Meyer: None declared, Silke Pitann: None declared, Antje Müller: None declared, Gabriela Riemekasten Consultant of: Cell Trend GmbH, Janssen, Actelion, Boehringer Ingelheim, Speakers bureau: Actelion, Novartis, Janssen, Roche, GlaxoSmithKline, Boehringer Ingelheim, Pfizer, Peter Lamprecht: None declared

AB0496 AUTOANTIBODIES TARGETING COMPLEMENT RECEPTORS 3A AND 5A1 ARE DECREASED IN ANCA-ASSOCIATED VASCULITIS AND CORRELATE WITH HIGHER RELAPSE RATE

Background:

Activation of the alternative and final common pathways have been shown in ANCA-associated vasculitis (AAV) (1). Circulating titers of C5a are elevated and correlate with disease activity in AAV. Binding to the corresponding G protein-coupled receptor (GPCR) C5aR1 enhances the influx of neutrophils, leading to ROS generation and severe necrotizing of vascular walls (2). Moreover, subsequent interaction of C5a with C5aR1 may represent a proinflammatory amplification loop (3). Blocking of the receptor is protective in a murine model in AAV (4). In humans, avacopan, a C5aR1-inhibitor showed promising results as glucocorticoid-sparing agent in two randomized phase II and one ongoing phase III clinicals trials in AAV (NCT02994927). Notably, disease-specific anti-GPCR autoantibody (aab) signatures have been found in different autoimmune diseases (5).

Objectives:

The aim of the present study was to examine whether (patho)physiological anti-C3aR and anti-C5aR1 aabs correlate with clinical findings in AAV, and whether this is linked to the clinical outcome.

Methods:

Sera and plasma of AAV patients [granulomatosis with polyangiitis (GPA), n=64; microscopic polyangiitis (MPA), n=26; eosinophilic granulomatosis with polyangiitis (EGPA), n=11] were measured by Elisa for circulating autoantibodies against complement receptors C3a (anti-C3aR aab) and C5a (anti-C5aR1 aab) and plasma levels of C3a and C5a. Expression of C3aR and C5aR1 on T-cells was determined using flow cytometry. Clinical data were assessed at the time of serum sampling and during follow-up for 48 months

Results:

GPA displayed low titers of anti-C3aR aab (GPA:5.33±2.54vs. HD:6.47±2.61, P=0.0031). Anti-C5aR1 aab were decreased in AAV, especially in GPA (GPA:1.02±1.07vs. HD:6.63±2.91, P=<0.0001). Plasma levels of C5a and anti-C5aR aab yielded an inverse correlation in AAV (r=-0.6813, P=0.0127). C5aR1 expression was increased on T-cells in GPA (CD4+C5aR1+T-cells: GPA:10.76±2.55%vs. HD:3.44±0.68%, P=0.0021; CD8+C5aR1+T-cells GPA:9.74±2.10%vs.HD:4.11±0.92%, P=0.0198). Reduced titers of anti-C5aR1 aab <0.45U/ml displayed an increased relapse risk for major organ involvement in GPA (HR 12.85, P=0.0014).

Conclusion:

As potential diagnostic marker, anti-C5aR1 aab titer may additionally be useful to monitor disease activity in AAV.

References:

[1]Chen M et al.Complement deposition in renal histopathology of patients with ANCA-associated pauci-immune glomerulonephritis.Nephrol Dial Transpl. 2009;24:1247-1252

[2]Schreiber A et al.C5a receptor mediates neutrophil activation an ANCA-induced glomerulonephritis.J Am Soc Nephrol. 2009; 20:289-298

[3]Lamprecht P et al.: Pathogenetic and clinical aspects of Anti-Neutrophil Cytoplasmic Autoantibody-associated vasculitides.Front Immunol.2018 Apr 9;9-680

[4]Xiao H et al.C5a receptor (CD88) blockade protects against MPO-ANCA GN.J Am Soc Nephrol. 2014;25(2):225-31

[5]Klapa S et al. Decreased endothelin receptor A autoantibody levels are associated with early ischaemic events in patients with giant-cell arteritis.Ann Rheum Dis2019 Oct;78(19):1443-1444

Disclosure of Interests:

Sebastian Klapa Grant/research support from: Actelion, Consultant of: Pfizer, Abbvie, Antje Müller: None declared, Andreas Koch: None declared, Anja Kerstein-Staehle: None declared, Wataru Kaehler: None declared, Harald Heidecke Shareholder of: Cell Trend GmbH, Employee of: Cell Trend GmbH, Speakers bureau: Cell Trend GmbH, Susanne Schinke Speakers bureau: Pfizer, Markus Huber-Lang: None declared, Martin Nitschke: None declared, Silke Pitann: None declared, Christian Karsten: None declared, Gabriela Riemekasten Consultant of: Cell Trend GmbH, Janssen, Actelion, Boehringer Ingelheim, Speakers bureau: Actelion, Novartis, Janssen, Roche, GlaxoSmithKline, Boehringer Ingelheim, Pfizer, Peter Lamprecht: None declared

AB0166 IMMUNOGLOBULIN G DERIVED FROM PATIENTS WITH SYSTEMIC SCLEROSIS IMPRINTS A PRO-INFLAMMATORY AND PRO-FIBROTIC PHENOTYPE IN MONOCYTE-LIKE THP-1 CELLS

Background:

Regulatory IgG autoantibodies directed against diverse G protein-coupled receptors (GPCR),i.e.antibodies with agonistic or antagonistic activity are abundant in human serum. The serum titers of autoantibodies targeting angiotensin II receptor 1 (AT1) and endothelin receptor A (ETA) are specifically altered in autoimmune diseases such as systemic sclerosis (SSc). Disease-promoting mechanisms regulated by anti-AT1and anti-ETAIgG are still elusive, but induction of pro-inflammatory and pro-fibrotic chemokines (CXCL8, CCL18) has been suggested to be one of them.

Objectives:

To determine the cytokine and phospho-kinase profiles induced in monocyte-like cells by IgG derived from SSc patients (SSc-IgG) enriched with anti-AT1and anti-ETAantibodies in comparison to IgG derived from healthy donors (IgG-HD).

Methods:

A monocyte-like cell line (THP-1) was culturedin vitroand stimulated with IgG (1 mg/ml) derived from SSc patients or HD in the presence of various inhibitors/blockers for 24h. Then, supernatants were analyzed by a human cytokine/chemokine array. Data were analyzed using bio-mathematical tools such as generalized t-test including the robust regression method from R/Bioconductor package LIMMA. In addition, THP-1 cells were culturedin vitroand stimulated with IgG (1 mg/ml) derived from SSc patients or HD for up to 30 minutes. Thereafter, cell lysates were assayed for the kinome employing a human phospho-kinase array. To validate potential effects of transcription factor inhibition, release of CXCL8 and CCL18 into the supernatant was measured by Elisa.

Results:

In general, SSc-IgG induced the release of most cytokines by THP-1 cells more pronouncedly than HD-IgG. The bio-mathematical analysis suggested that stimuli, responsible for the shift of the THP-1 cell cytokine profile, are more abundant in SSc-IgG than in HD-IgG. Based upon these findings a gene set enrichment analysis for transcription factors yielded the transcription factors NF-κB, AP-1, and PRDM1 (Blimp-1) as putative major regulatory hubs for the response of THP-1 cells to SSc-IgG. Further, SSc-IgG altered the phosphorylation status of several proteins, indicative of an involvement of MAPK and/or JAK/STAT pathways. Interestingly, a role for AP-1 was also proposed by the inhibition of CXCL8 and CCL18 release following pretreatment of THP-1 cells with an AP-1 blocker.

Conclusion:

Herein, we demonstrate that IgG of SSc patients, enriched with anti-AT1and anti-ETAautoantibodies drives THP-1 cells towards a general pro-inflammatory and pro-fibrotic phenotype, which is reflected by broad changes in the secretome and kinome of these cells. Furthermore, our results highlight AP-1 as critical regulator of gene transcription of CXCL8 and CCL18 in a monocyte-like cell line.

References:

[1]Cabral-Marques O, Marques A, Giil LM, De Vito R, Rademacher J, Günther J, Lange T, Humrich JY, Klapa S, Schinke S, et al. GPCR-specific autoantibody signatures are associated with physiological and pathological immune homeostasis.Nat Commun(2018)9:5224. doi:10.1038/s41467-018-07598-9

[2]Günther J, Kill A, Becker MO, Heidecke H, Rademacher J, Siegert E, Radi M, Burmester G-R, Dragun D, Riemekasten G. Angiotensin receptor type 1 and endothelin receptor type A on immune cells mediate migration and the expression of IL-8 and CCL18 when stimulated by autoantibodies from systemic sclerosis patients.Arthritis Res Ther(2014)16:R65. doi:10.1186/ar4503

Disclosure of Interests:

Anja Dalmann: None declared, Sripriya Murthy: None declared, Melanie Wannick: None declared, Georgios Eleftheriadis: None declared, Antje Müller: None declared, Detlef Zillikens: None declared, Hauke Busch: None declared, Christian Sadik: None declared, Gabriela Riemekasten Consultant of: Cell Trend GmbH, Janssen, Actelion, Boehringer Ingelheim, Speakers bureau: Actelion, Novartis, Janssen, Roche, GlaxoSmithKline, Boehringer Ingelheim, Pfizer

THU0025 MICRO-RNA DIFFERENTIALLY REGULATE THE ALTERNATIVE PRTN3-MRNA IN GRANULOMATOSIS WITH POLYANGIITIS

Background:

Micro-RNAs (miRNA) are short non-coding RNAs that regulate inflammation mostly by translational repression. Previously, we screened 847 miRNAs in nasal tissue from GPA patients and found a disease associated alteration of miRNA expression compared to healthy controls and chronic rhinosinusitis. MiR-184 was most over expressed in nasal tissue from GPA (13.4x). The dual-luciferase reporter assay confirmed a significant reduction of Proteinase-3 (PRTN3) expression by miR-184 (1).

PRTN3 transcripts with an alternative 3’ untranslated region (UTR) have been described in GPA (2). The pathophysiological relevance of this alternative transcript remains unclarified.

Objectives:

To identify new miRNA targets of potential pathophysiological relevance in GPA, we validated the effect of the 21 most dysregulated miRNAs on the mRNA of PRTN3. Further, we included the alternative PRTN3 mRNA in our screen to look for new regulatory differences.

Methods:

The inhibitory capacity of miRNAs on Proteinase-3 mRNA was estimated by a dual-luciferase reporter system. The sequences of the alternative (132bp longer) and the regular 3’UTR-PRTN3 were cloned and inserted into the pmirGLO vector and co-transfected with 21 miRNA mimics into HeLa cells. Co-transfection withCaenorhabditis elegansmiRNA 67 mimic (cel-miR-67) was used as negative control. Statistical significance was evaluated by students t-test adjusted for multiple comparisons (Holm-Sidak).

Results:

For 18 of 21 investigated miRNAs no effects could be observed on the alternative and the regular 3’UTR-PRTN3. But there were remarkable differential effects of let-7f, miR-184 and miR-708. Let-7f (-29,2%) and miR-708 (-23,6%) both showed a suppression of the alternative 3’UTR-PRTN3 but no effect on the regular 3’UTR-PRTN3 while miR-184 only suppressed the regular 3’UTR (-17,5 %) and not the alternative variant (fig. 1-2).

Fig. 1.

Dual-luciferase reporter assay with the regular 3’UTR of PRTN3 cloned into the pmirGLO vector compared to empty vector (NTC). Significant effect for miR-184 (17,5 %), miR-708 no effect and let-7f small but not significant reduction in luciferase activity (12,3 %). Data represent 3 independent experiments with triplicate measurements. miR-184 was tested 6 times. *P<0.05; ns = not significant; error bars display standard deviation.

Fig. 2.

Dual-luciferase reporter assay with the alternative 3’UTR of PRTN3. Significant effects of let-7f (29,2 %) and miR-708 mimic (23,6 %) but no significant effects of miR-184 of luciferase activity. 3 independent experiments with triplicate measurements. *P<0.05

Conclusion:

Disease specific miRNA signatures together with an increased PRTN3 level and in alternative PRTN3 mRNA in GPA suggest a dysregulation of PRTN3 expression in GPA. To our knowledge this is the first analysis in GPA showing that miRNAs can differentially regulate the expected and the alternative 3’UTR variants of PRTN3-mRNA. As miR-184 is markedly upregulated in GPA, a repression of PRTN3 is to be anticipated, possibly as a reaction to previous neutrophil activation with PRTN3 overexpression. Our findings also strengthen the potential pathophysiological role of the alternative PRTN3 mRNA.

References:

[1]Schinke S et alPROTEINASE-3 REGULATING MICRO-RNA IN GRANULOMATOSIS WITH POLYANGIITIS. Ann Rheum Dis 2019 (78 Suppl 2):437

[2]McInnes E et alDysregulation of Autoantigen Genes in ANCA-Associated Vasculitis Involves Alternative Transcripts and New Protein Synthesis J Am Soc Nephrol. 2015 26(2): 390–399

Acknowledgments:

Vasculitis foundation for funding

Disclosure of Interests:

Nick Reichard: None declared, Anja Kerstein-Staehle: None declared, Antje Müller: None declared, Gabriela Riemekasten Consultant of: Cell Trend GmbH, Janssen, Actelion, Boehringer Ingelheim, Speakers bureau: Actelion, Novartis, Janssen, Roche, GlaxoSmithKline, Boehringer Ingelheim, Pfizer, Peter Lamprecht: None declared, Susanne Schinke Speakers bureau: Pfizer

AB0159 INTERLEUKIN-16 PLAYS A ROLE IN THE PATHOGENESIS OF SYSTEMIC SCLEROSIS

Background:

Systemic sclerosis (SSc) is an autoimmune disorder with chronic and persistent inflammation. Interleukin-16 was originally described as a factor that could attract activated T cells in humans [1]. Elevated amounts of IL-16 have been demonstrated in SSc [2].

Objectives:

This study was undertaken to find out if IL-16 is associated with clinical characteristics of SSc.

Methods:

IL-16 was measured by Elisa in serum of patients with SSc (n=119) and healthy controls (n=50). Further, the presence of active IL-16 in mononuclear cells from peripheral blood of SSc patients (n=10) was examined by Western blot. Statistical analyses were done employing Graph Pad prism software (v 8). Patients with SSc were characterized based upon epidemiological and clinical parameters.

Results:

The serum concentration of IL-16 was higher in patients with SSc than in healthy controls (272.7±165.4 vs 172.8±64.84 pg/ml, p<0.0001). Further, the difference in the IL-16 serum concentration was more prominent in females (265.6±174.2 vs 160.1±53.37 pg/ml, p=0.0002) than in males (287.1±144.1 vs 187.6±74.64 pg/ml, p=0.0034). In addition, the concentration of IL-16 was elevated in patients with diffuse SSc compared to limited SSc (p=0.0206). The concentration of IL-16 in serum of SSc patients positively correlated with CRP (n=115, r=0.49, p<0.0001). There was a weak positive correlation between IL-16 in serum of SSc patients and the mRSS (n=112, r=0.22, p=0.0175). Noteworthy, the concentration of IL-16 was heightened in SSc patients with lung fibrosis compared to SSc patients without lung fibrosis (p=0.009). The ROC value of SSc patients with lung fibrosis was 0.64 (95%CI: 0.58-0.83). Moreover, active IL-16 derived from peripheral blood mononuclear cells (PBMC) of SSc patients with lung fibrosis was present in higher amounts compared to PBMC of SSc patients without lung fibrosis (5 vs 5, p=0.0557).

Conclusion:

Our results confirm and extend previous data by showing not only an increased concentration of IL-16 in the circulation of SSc patients, but new findings pointing towards a role of IL-16 for contributing to lung fibrosis in SSc.

References:

[1]Cruikshank, W. and D.M. Center, Modulation of lymphocyte migration by human lymphokines. II. Purification of a lymphotactic factor (LCF). J Immunol, 1982. 128(6): p. 2569-74.

[2]Kawabata, K., et al., IL-16 expression is increased in the skin and sera of patients with systemic sclerosis. Rheumatology (Oxford), 2019.

Disclosure of Interests:

Jiao Luo: None declared, Anja Kerstein-Staehle: None declared, Sara Comduehr: None declared, TatjanaKathleen Dreyer: None declared, Antje Müller: None declared, Susanne Schinke Speakers bureau: Pfizer, Gabriela Riemekasten Consultant of: Cell Trend GmbH, Janssen, Actelion, Boehringer Ingelheim, Speakers bureau: Actelion, Novartis, Janssen, Roche, GlaxoSmithKline, Boehringer Ingelheim, Pfizer