B-Lymphocyte stimulator (BLyS) up-regulation in mixed cryoglobulinaemia syndrome and hepatitis-C virus infection

Rheumatology 2007;46:37–43 Advance Access publication 30 May 2006 doi:10.1093/rheumatology/kel174 B-Lymphocyte stimulator (BLyS) up-regulation in mixed cryoglobulinaemia syndrome and hepatitis-C virus infection M. Fabris1, L. Quartuccio1, S. Sacco1, G. De Marchi1, G. Pozzato2, C. Mazzaro3, G. Ferraccioli4, T. S. Migone5 and S. De Vita1 Objectives. To investigate the role of B-Lymphocyte stimulator (BLyS) in mixed cryoglobulinaemia syndrome (MCsn), a systemic vasculitis associated with a high risk to develop lymphoma, since BLyS up-regulation may favour both autoimmunity and lymphoproliferation. Methods. BLyS serum levels were analysed by enzyme-linked immunosorbent assay (positive when >0.85 ng/ml) in 66 patients with MCsn, 54 (81.8%) of whom were positive for hepatitis-C virus (HCV) infection. Thirty-three HCV-positive patients without MCsn were also studied. Patients were compared with 48 healthy blood donors (HBDs). BLyS modifications after antiviral therapy were also studied. Results. A significantly higher frequency of BLyS serum positivity was detected both in MCsn patients and in HCV-positive patients without MCsn (37.9 and 30.3%, respectively) when compared with HBDs (4.2%) (P < 0.0001 vs MCsn and P ¼ 0.0026 vs HCV-positive patients without MCsn, respectively). BLyS appeared significantly higher in MCsn (3.70
2.97 ng/ml) than in HCV-positive patients without MCsn (1.56
0.63 ng/ml; P ¼ 0.0044). BLyS expression did not correlate with rheumatoid factor levels, cryoglobulin levels or definite MCsn-related systemic features. High BLyS levels were significantly associated only with MCsn-related overt lymphoproliferative disorder. Finally, antiviral treatment significantly increased BLyS levels, independently from HCV-RNA negativization. However, BLyS normalization was noticed after both HCV-RNA negativization and suspension of antiviral therapy by preliminary data. Conclusions. BLyS is up-regulated and may play a pathogenetic role in a fraction of patients with MCsn, similarly to other autoimmune diseases. HCV infection likely represents the early event leading to BLyS up-regulation in this setting. BLyS is up-regulated during antiviral treatment. Overall, these data provide new insights for BLyS and virus-related autoimmunity, lymphoproliferation and possible treatment strategies. KEY WORDS: BLyS, BAFF, cryoglobulinemia, HCV, rheumatoid arthritis, SLE, Sjögren’s syndrome. Introduction Mixed cryoglobulinaemia syndrome (MCsn) is a systemic vasculitis prevalently mediated by immune complexes, i.e. mixed cryoglobulins, and characterized by non-neoplastic B-cell lymphoproliferation favouring the progression into frank B-cell non-Hodgkins lymphoma (NHL) in 5–10% of patients [1–3]. Cryoglobulins are formed by cold precipitable immunoglobulins, immune complexes formed by a rheumatoid factor (RF), usually immunoglobin M with k light chain (IgMk), monoclonal in type II, polyclonal in type III MC, that binds polyclonal immunoglobin G (IgG). The hepatitis-C virus (HCV) infection is the aetiological agent in the large majority of MCsn cases [4, 5], and chronic antigenic stimulation by HCV is considered a key mechanism sustaining the proliferation of the RF-secreting B-cell clones [6]. Cryoglobulins are detected in up to 40% of HCV-positive subjects, with MCsn in 1–5%. In the minority of HCV-negative MCsn cases, other infectious agents or autoimmune and lymphoproliferative conditions [e.g. hepatitis-B virus (HBV) and Sjögren’s syndrome (SS)] may be present [2, 7]. Besides chronic antigenic stimulation, cytokines and growth factors may also play a key role in sustaining B-cell overactivation in this settings, though limited data are available at present [2, 8, 9]. Recently, a new member of the tumour necrosis factor (TNF) superfamily called B-Lymphocyte stimulator (BLyS) was reported to be highly expressed in autoimmune diseases characterized by B-cell overactivation, such as systemic lupus erythematosus (SLE), SS and rheumatoid arthritis (RA) [10–13], all pre-disposing to NHL development [14]. Abnormal production of BLyS disturbs immune tolerance by allowing the survival of autoreactive B-cells, thus triggering autoimmune disorders [15–17]. BLyS acts essentially by inhibiting B-cell apoptosis [15], and B-cell apoptosis is implicated in the pathogenesis of MCsn [18] as well as of SS [19], RA [20] and SLE [21]. 1 Division of Rheumatology, DPMSC, School of Medicine, University of Udine, 2Internal Medicine, UCO, University of Trieste, 3Division of Internal Medicine 2, S. Maria degli Angeli Hospital, Pordenone, 4Department of Rheumatology, UCSC, School of Medicine, Catholic University of Rome, Italy and 5 Human Genome Sciences, Rockville, MD, USA. Received 10 January 2006; revised version accepted 18 April 2006. Correspondence to: Prof. S. De Vita, Chief, Clinic of Rheumatology, DPMSC, University of Udine, 33100 Udine, Italy. E-mail: 37 ß The Author 2006. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: The online version of this article has been published under an open access model. Users are entitled to use, reproduce, disseminate, or display the open access version of this article for non-commercial purposes provided that: the original authorship is properly and fully attributed; the Journal and Oxford University Press are attributed as the original place of publication with the correct citation details given; if an article is subsequently reproduced or disseminated not in its entirety but only in part or as a derivative work this must be clearly indicated. For commercial re-use, please contact Downloaded from https://academic.oup.com/rheumatology/article-abstract/46/1/37/2255892 by guest on 09 May 2018 38 M. Fabris et al. BLyS is expressed by monocytes, dendritic cells, T-cells, neutrophils and synoviocytes [22–26], and it acts on mature B-lymphocytes promoting differentiation, proliferation, survival (through Bcl2 up-regulation) and finally determining an increase in Ig-secreting cells [15, 16]. BLyS transgenic mice develop a lupus-like syndrome, followed by sialoadenitis and B-cell salivary gland infiltration and finally a B-cell lymphoma [17]. No data are available regarding BLyS either in MCsn or in the course of HCV infection. In the present study, significantly increased BLyS serum levels were demonstrated in MCsn. Of note, BLyS appeared also up-regulated in HCV-infected patients without MCsn. Then, HCV infection may represent an early pathogenetic event leading to BLyS overexpresssion. Such novel information may be relevant when exploring BLyS de-regulation in autoimmune diseases of unknown aetiology [14]. Interestingly, BLyS up-regulation during antiviral treatment and BLyS normalization after HCV-RNA negativization and treatment suspension were also noticed in preliminary studies. Methods Sixty-six consecutive unselected patients with MCsn, classified according (...truncated)