Quantification of Antifibrillarin (anti-U3 RNP) Antibodies: A New Insight for Patients with Systemic Sclerosis

Audrey Benyamine (1, 2) , Daniel Bertin (3) , Noémie Resseguier (4, 5) , Xavier Heim (1, 3) , Julien Bermudez (1) , David Launay (6, 7, 8) , Sylvain Dubucquoi (7) , Adrian Hij (9, 10, 11) , Dominique Farge (9, 10, 11, 12) , Alain Lescoat (13) , Isabelle Bahon-Riedinger (13) , Nouria Benmostefa (14) , Luc Mouthon (14) , Jean-Robert Harlé (4) , Gilles Kaplanski (1, 3) , Pascal Rossi (2, 1) , Nathalie Bardin (1, 3) , Brigitte Granel (1, 2)

1 C2VN - Centre recherche en CardioVasculaire et Nutrition = Center for CardioVascular and Nutrition research
2 Hôpital Nord [CHU - APHM]
3 LA CONCEPTION - Hôpital de la Conception [CHU - APHM]
4 TIMONE - Hôpital de la Timone [CHU - APHM]
5 AMU - Aix Marseille Université
6 INFINITE (Ex-Liric) - Institute for Translational Research in Inflammation - U 1286
7 CHRU Lille - Centre Hospitalier Régional Universitaire [CHU Lille]
8 CeRAINO - Centre National de Référence des Maladies Auto-Immunes Systémiques Rares du Nord et Nord-Ouest de France
9 AP-HP - Hopital Saint-Louis [AP-HP]
10 FAI2R - Center of reference for rare systemic autoimmune diseases
11 (EA_3518) - Recherche clinique appliquée à l'hématologie
12 McGill University = Université McGill [Montréal, Canada]
13 Centre Hospitalier Universitaire de Rennes [CHU Rennes] = Rennes University Hospital [Ponchaillou]
14 Hôpital Cochin [AP-HP]

Background: The detection of additional autoantibodies is of great concern in systemic sclerosis (SSc) when those included in the ACR/EULAR classification are negative. In this context, the interest of antifibrillarin (anti-U3RNP) autoantibodies (AFAs) in the routine evaluation of SSc remains unclear. We aimed to assess the relevance of AFAs and their clinical association in SSc patients. Methods: In a multicenter observational retrospective study, we collected immunological and clinical data associated with AFA positivity in SSc (n = 42) and non-SSc patients (n = 13). Patients with SSc negative for AFAs (n = 83) were considered as a control group. AFAs were detected by indirect immunofluorescence (IIF) using HEp-2 cells, EliA or immunoblot techniques. Results: We confirmed a typical nuclear IIF pattern and showed that AFAs are mostly exclusive towards SSc conventional autoantibodies. Although also observed in non-SSc patients, high levels of AFAs with the ELiA technique allowed the diagnosis of SSc. Compared to AFA-negative SSc patients, AFA-positive SSc patients more frequently exhibited visceral involvements. They more frequently suffered from the diffuse cutaneous form and had a higher global severity of the disease. Conclusions: We demonstrate the usefulness of quantifying AFAs in the immunological exploration of SSc, especially when patients are seronegative for SSc conventional autoantibodies and display a typical IIF pattern. AFAs might constitute an interesting marker of SSc severity.

Mots clés: anti-U3 RNP antibodies; antifibrillarin antibodies; autoantibodies; systemic sclerosis

Domaines: Sciences du Vivant [q-bio]

Audrey Benyamine, Daniel Bertin, Noémie Resseguier, Xavier Heim, Julien Bermudez, et al.. Quantification of Antifibrillarin (anti-U3 RNP) Antibodies: A New Insight for Patients with Systemic Sclerosis. Diagnostics, 2021, 11 (6), pp.1064. ⟨10.3390/diagnostics11061064⟩. ⟨hal-03653470⟩