Abstract
IntroductionPlasma cells residing in inflamed tissues produce antibodies in chronic inflammatory and systemic autoimmune diseases. This study examined if plasma cells, located within inflamed nasal tissue in granulomatosis with polyangiitis (GPA), express features potentially associated with the autoimmune and destructive character of this disease.MethodsIg gene mutation patterns of individual tissue-derived plasma cells from GPA (n = 5) were analyzed, by using laser-assisted microdissection followed by semi-nested polymerase chain reaction (PCR). Signs of B-lymphocyte maturation (ectopic lymphoid structures, ELS) and survival (a proliferation-inducing ligand, APRIL; B-cell maturation antigen, BCMA; transmembrane-activator and calcium modulator and cyclophilin interactor, TACI; receptor activator of nuclear factor κB ligand, RANKL) were examined in nasal tissues or serum, respectively, by using immunohistochemistry/fluorescence and enzyme-linked immunosorbent assay, ELISA.ResultsPlasma-cell derived Ig genes (light- and heavy-chain pairs, n = 4; heavy chains, n = 33) resembled mutation patterns seen in other autoimmune diseases, predominantly displaying selection against replacement mutations within the framework region of Ig genes (10 of 15), which is responsible for structural integrity. Ectopic lymphoid structures were similar between GPA and a disease control (that is, unspecific chronic rhinosinusitis. However, histomorphologic features distinguishing GPA from rhinosinusitis (that is, neutrophilic microabscess and granuloma) expressed considerable amounts of membrane-associated and secreted APRIL, respectively. The latter was co-localized with CD138 and found in close proximity to cells expressing IgG, TACI, and BCMA. Interestingly, plasma cells strongly expressed receptor activator of nuclear factor κB ligand (RANKL), apart from fibroblast-like cells.ConclusionsPlasma cells within granulomatous inflammation appear to display features that might be required for autoreactivity and, possibly, RANKL-mediated destruction in GPA.
Highlights
Plasma cells residing in inflamed tissues produce antibodies in chronic inflammatory and systemic autoimmune diseases
Altered mutation pattern of plasma cell-derived Ig genes in nasal tissue in granulomatosis with polyangiitis (GPA) Of 41 productively rearranged Ig V region gene fragments, representing 37 dispersely distributed CD138+ plasma cells, 15 (37%) yielded significantly mutated Ig genes compared with corresponding germline genes (Table 1; Additional file 1: Table S3)
Selection was calculated based on replacement to silent mutation ratios in a complementarity-determining region (CDR) and framework region (FR), according to [18]
Summary
Plasma cells residing in inflamed tissues produce antibodies in chronic inflammatory and systemic autoimmune diseases. This study examined if plasma cells, located within inflamed nasal tissue in granulomatosis with polyangiitis (GPA), express features potentially associated with the autoimmune and destructive character of this disease. We detected mutated Ig variable (V) region genes in nasal tissue in GPA, and some of the CD20+ B cells produced autoantibodies [7]. Relapses occur, suggesting that plasma cells, surviving in niches and producing autoantibodies [11], could be responsible. To search for alterations, plasma cells derived from inflamed nasal tissue in GPA were analyzed in terms of mutation pattern of their Ig genes and compared with controls [13], after laser-assisted microdissection and semi-nested PCR
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