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

Incidence and risk factors for community-acquired acute gastroenteritis in north-west Germany in 2004

In developed countries, acute gastroenteritis (AGE) is a major source of morbidity. However, only a few studies have estimated its incidence and the associated medical burden. This population-based study determined the incidence of community-acquired AGE patients seeking medical care and the relative role of various pathogens. Stool samples from patients with AGE presenting to a general practitioner (GP), pediatrician, or specialist in internal medicine for that reason were screened for various bacterial and viral enteropathogens. A control group was established as well. Incidences were calculated by the number of positive patients divided by the general population. The study was performed in north-west Germany in 2004. The incidence of AGE patients requiring medical consultation was 4,020/100,000 inhabitants. Children (<5 years of age) were at the highest risk (13,810/100,000 inhabitants). Of the patients, 6.6% were tested positive for an enteropathogenic bacteria and 17.7% for a viral agent. The predominant pathogens were norovirus (626/100,000) and rotavirus (270/100,000). Salmonella was the most frequently detected bacteria (162/100,000). The results presented confirm AGE and, specifically, AGE of viral origin as a major public health burden in developed countries.

[Acute pancreatitis - association with a Campylobacter coli-infection]

A 37-year-old male presented with intermittent abdominal pain and 9 kg weight loss within 3 weeks. Gastroscopy showed no pathological findings, coloscopy showed a colitis limited to the left flexure. Histology revealed a sustained infectious enterocolitis. A culture of the patient's stool was positive for CAMPYLOBACTER COLI. Because of the recurrent abdominal discomfort and weight loss the patient was admitted to the hospital. Ultrasound and multislice spiral computed tomography showed an acute oedematous pancreatitis. No other causes for the pancreatitis were found, the only remaining possibility was a CAMPYLOBACTER COLI-associated pancreatitis. Under symptomatic therapy the patient recovered definitively. An administration of antibiotics was not necessary.

[Motor potentials following spinal and transcranial stimulation: normal values for recording without voluntary pre-innervation]

The transcranial motor stimulation with a special, short discharging stimulator can assess the conduction of central motor pathways. Voluntary preinnervation of certain muscles leads to amplitude augmentation and allows reduction of the stimulus intensity. Preinnervation is impossible, if comatose patients are studied or if the method is used for intraoperative monitoring. We examined the spinal and transcranial stimulated motor responses of the muscle opponens pollicis without preinnervation in 18 healthy volunteers. The latencies after hemispheric stimulation showed an increase of latency of more than 2.5 ms compared with normative data from the literature which is significant on the .05-level. The central conduction time was prolonged also. The latencies of the spinal stimulated muscle potentials are comparable under both conditions. It is concluded that for intraoperative monitoring or the assessment of motor function in comatose patients one has to relay on normative values achieved without preinnervation.

[The influence of umbilical cord structure on the course of pregnancy and parturition (author's transl)]

A series of 549 not selected placentas and umbilical cords were examined to show the influence of the different development of the umbilical cord structure on the umbilical cord perfusion and the course of parturition. For this purpose the quantity of Wharton's jelly, the spiraling of the umbilical vessels as well as the length of the cord are defined. At the same time anatomical pecularities and complications like umbilical cord torsions and true knots are considered. To judge the decisive condition of the newborn and with that the course of parturition, the pH-value of umbilical artery blood is determined. The analysis results that umbilical cords with much Wharton's jelly and with spiraling vessels are converted into an association with extremely better value than those with little jelly and less spiraling vessels. Short and rich jellied umbilical cords show a significantly lower incidence of loops around the fetal body. A similar trend can be demonstrated for umbilical cords with strong spiraling arteries. Rare phenomena like velamentous insertion, haematomas, edemas and true knots of the cords etc. proved to have no influence on the course of parturition in our relatively small examination series.