Neurology International 2013; volume 5:e4 Expression of B-cell activating the NF-kB-pathway.4 BAFF is usually expressed by macrophages, monocytes, and T-, but not B- Correspondence: Tobias Birnbaum, Department factor, a proliferating inducing cells. It binds to three receptors: BAFF receptor of Neurology, Ludwig-Maximilians University, ligand and its receptors (BAFF-R), B-cell maturation antigen (BCMA) Marchioninistr. 15, 81377 Munich, Germany. in primary central nervous and transmembrane activator and calcium Tel. +49.8970950 - Fax: +49.8951603677. system lymphoma modulator cyclophilin ligand interactor (TACI). E-mail: [email protected] APRIL binds to BCMA and TACI. The BAFF/APRIL system might play an important Key words: PCNSL; BAFF; APRIL; TACI; BCMA 1 1 Tobias Birnbaum, Sigrid Langer, role in the pathogenesis of systemic B-cell 2 1 Conflict of interests: the authors report no poten- Sigrun Roeber, Louisa von Baumgarten, 4-7 malignancies. However, this signaling path- tial conflict of interests. Andreas Straube1 way has not been systematically evaluated in Departments of 1Neurology and PCNSL to date. Aim of this study was to assess Contributions: TB, SL, AS, were responsible for 2Neuropathology, Ludwig-Maximilians the expression profile of the BAFF/APRIL sys- the conception of the study, analysis and inter- University, Munich, Germany tem in PCNSL. pretation of data; TB, wrote the manuscript; LvB, SL, SR, were responsible for immunohistochemi- cal staining, acquisition of photographs and preparing figures. Abstract Materials and Methods Received for publication: 14 September 2012. Revision received: 12 February 2013. B-cell activating factor belonging to the Formalin-fixed, paraffin-embedded tissue Accepted for publication: 25 February 2013. tumor necrosis factor family (BAFF) and a pro- sections from biopsy specimens of five newly liferating inducing ligand (APRIL) might play diagnosed PCNSL were assessed. Antigen This work is licensed under a Creative Commons an important role in the pathogenesis of sys- retrieval was done with target retrieval solution Attribution NonCommercial 3.0 License (CC BY- NC 3.0). temic B-cell malignancies. However, the (S1699, Dako, Germany) for 10 min at 98.5°C. Endogenous peroxidase activity was reduced by BAFF/APRIL system has not been systematical- ©Copyrightonly T. Birnbaum et al., 2013 ly evaluated in primary central nervous system incubation with 3% H2O2 for 10 min. We used Licensee PAGEPress, Italy lymphoma (PCNSL) to date. We assessed the the following primary antibodies: rabbit anti- Neurology International 2013; 5:e4 expression of BAFF, APRIL and its receptors human BAFF (ab117256, dilution 1:12.5), goat doi:10.4081/ni.2013.e4 BAFF-R (BAFF receptor), BCMA (B-cell matu- anti-human APRIL (ab110848, dilution 1:100), ration antigen) and TACI (transmembrane rabbit anti-human BAFF-R (ab5965, dilutionuse activator and calcium modulator cyclophilin 1:100), rabbit anti-human BCMA (ab115315, ligand interactor) in five PCNSL specimens by dilution 1:50), rabbit anti-human TACI ed using two different antibodies. In contrast, immunohistochemical staining. We found (ab79023, dilution 1:50), mouse anti-human APRIL was expressed in variable amounts in extensive expression of BAFF and weak to CD20 [ab9475 (L26), dilution 1:35], rabbit anti- 4/5 specimens. Expression of BAFF and APRIL moderate expression of APRIL, BAFF-R, BCMA, human CD3 (ab5690, dilution 1:100) (all was not restricted to stromal or inflammatory and TACI in all specimens. CD20 positive cells ABCAM, Cambridge, MA, USA), mouse anti- cells, but was found mainly in CD20 positive showed expression of both ligands and recep- human CD68 (PG-M1, M 0876, dilution 1:100, tumor cells. Furthermore, all tumors showed at tors at the same time. Our results indicate that Dako, Glostrup, Denmark) and rabbit anti- least weak expression of all three receptors autocrine stimulation of the BAFF/APRIL sys- human BAFF (ABIN740175, dilution 1:50, anti- (Table 1, Figure 1). Two tumors showed exten- tem might be involved in the pathogenesis of bodies-online inc., Atlanta, GA, USA). The fol- sive expression of TACI and weak to moderate PCNSL. lowing secondary antibodies were used: horse- expression of BCMA and BAFF-R. The remain- radish peroxidase conjugated polyclonal goat ing specimens showed weak to moderate anti-rabbit (dilution 1:100), horseradish peroxi- expression of all three receptors. As for the lig- dase conjugated polyclonal goat anti-mouse ands, expression of BAFF-R, BCMA and TACI Introduction (dilution 1:200, both Dako, Glostrup, Denmark), was found mainly within CD20 positive cells. Non-commercialand horseradish peroxidase conjugated poly- All in all, most CD20 positive cells expressed Primary central nervous system lymphoma clonal donkey anti-goat (dilution 1:125, not only BAFF/APRIL, but also at least one cor- (PCNSL) is a rare variant of extranodal non- Dianova, Germany). Visualization was done responding receptor. Hodgkins lymphoma (NHL). Cure is achieved with DAB Chromogen (Dako, Glostrup, only in a minority of patients using high-dose Denmark). Haematoxylin was used for counter- chemotherapy with or without whole brain staining. The ethics committee of the irradiation.1 However, combined chemoradio- University of Munich approved the study. Discussion and Conclusions therapy often is associated with severe neuro- toxicity leading to dementia. Therefore, new Expression of components of the treatment targets are urgently needed. BAFF/APRIL signaling pathway has been Little is known about the pathogenesis of Results shown in various systemic lymphomas.4-8 PCNSL. Increased expression of nuclear factor Overexpression of APRIL has been correlated kappa-B (NF-kB)-regulated genes has been We evaluated tissue sections from five with higher aggressiveness of B-cell lym- detected suggesting that this signaling path- patients with newly-diagnosed PCNSL. All phomas and expression of TACI has been asso- way might be of particular importance.2,3 B-cell tumors were histologically classified as diffuse ciated with poor prognosis in Burkitt lym- activating factor belonging to the tumor necro- large B-cell lymphoma (DLBCL). phoma.6,9 Another study suggested that BAFF sis factor family (BAFF) and a proliferating Immunohistochemistry revealed extensive is able to decrease apoptosis and to enhance inducing ligand (APRIL) physiologically stimu- nuclear expression of BAFF in all specimens survival of malignant B-cells.8 Furthermore, late survival of B-cells through activation of (Table 1, Figure 1). BAFF staining was validat- patients with increased serum BAFF levels had [page 10] [Neurology International 2013; 5:e4] Article a worse prognosis and BAFF levels correlated expression of mRNA for BAFF and its receptors expressed by astrocytes since they had found with transformation to a more aggressive in five PCNSL specimens. Evaluation of expres- BAFF-expressing astrocytes in the context of tumor phenotype.8 sion of the corresponding proteins, however, multiple sclerosis lesions. In contrast, our So far, only one report deals with this signal- was done only for BAFF-R by immunohistochem- results show for the first time, that CD20 posi- ing pathway in PCNSL: Krumbholz et al. found istry.10 The authors assumed that BAFF might be tive tumor cells themselves extensively produce BAFF. Therefore, rather autocrine than paracrine stimulation of this signaling pathway might promote proliferation of lymphoma cells. These results indicate a pathogenic role of the Table 1. Semi-quantitative assessment of expression of the BAFF/APRIL system in the dif- BAFF/APRIL system not only in systemic B-cell ferent tumor specimens. lymphomas, but also in PCNSL. Therefore, this PCNSL BAFF APRIL BAFF-R BCMA TACI signaling pathway might represent a new treat- ment target. Indeed, Lyu et al. found a signifi- E123 +++ ++ + ++ +++ cant antitumor activity of a BAFF fusion toxin in E236 +++ ++ ++ ++ ++ DLBCL cell lines, which expressed BAFF recep- E370 +++ + ++ + +++ tors.11 Other groups recently achieved promising E582 +++ -+++results using BAFF-mediated targeting of liposo- E753 +++ +++++ mal vincristine to malignant B-cells or mono- 12,13 PCNSL, primary central nervous system lymphoma; BAFF, B-cell activating factor belonging to the tumor necrosis factor family; APRIL, a prolif- clonal antibodies directed against APRIL. erating inducing ligand; BAFF-R, BAFF receptor; BCMA, B-cell maturation antigen; TACI, transmembrane activator and calcium modulator Further in vitro and in vivo studies should cyclophilin ligand interactor. address the role of the BAFF/APRIL system in - negative; + <30% positive cells; ++ 30-60% positive cells; +++ >60% positive cells. PCNSL and analyze whether blocking this sig- naling pathway might be beneficial in the treatmentonly of this disease. References use 1. Roth P, Korfel A, Martus P, Weller M. Pathogenesis and management of primary CNS lymphoma. Expert Rev Anticancer Ther 2012;12:623-33. 2. Courts C, Montesinos-Rongen M, Martin- Subero JI, et al. Transcriptional profiling of the nuclear factor-kappaB pathway identi- fies a subgroup of primary lymphoma of the central nervous system with low BCL10 expression. J Neuropathol Exp Neurol 2007;66:230-7. 3. Montesinos-Rongen M, Schmitz R, Brunn A, et al. Mutations of CARD11 but not TNFAIP3 may activate the NF-kappaB pathway in primary CNS lymphoma. Acta Neuropathol 2010;120:529-35. 4. Mackay F, Tangye SG. The role of the Non-commercial BAFF/APRIL system in B cell homeostasis and lymphoid cancers. Curr Opin Pharmacol 2004;4:347-54. 5. Wada K, Maeda K, Tajima K, et al. Expression of BAFF-R and TACI in reactive lymphoid tissues and B-cell lymphomas. Histopathology 2009;54:221-32. 6. Moreaux J, Veyrune JL, De Vos J, Klein B. APRIL is overexpressed in cancer: link with tumor progression. BMC Cancer Figure 1. Immunohistochemical stainings of specimen E582: Haematoxylin & Eosin 2009;9:83. staining (A) shows densely packed lymphoid tumor cells, which are positive for CD20 7. Rodig SJ, Shahsafaei A, Li B, et al. BAFF-R, (B). Reactive CD3 positive T cells (C) and CD68 positive microglial cells (D) are found the major B cell-activating factor receptor, within the tumor mass.