Vimentin Is a Dominant Target of In Situ Humoral Immunity in Human Lupus Tubulointerstitial Nephritis

Abstract

Objective In lupus nephritis (LuN), severe tubulointerstitial inflammation (TII) predicts progression to renal failure. Severe TII is associated with tertiary lymphoid neogenesis and in situ antigen-driven clonal B cell selection. The autoantigen(s) driving in situ B-cell selection in TII are not known. This study aimed to identify the dominant driving autoantigen(s). Methods Single CD38+ or Ki-67+ B cells were laser captured from seven LuN diagnostic biopsies. Eighteen clonally expanded immunoglobulin heavy and light chain variable region pairs were cloned and expressed as monoclonal antibodies. Seven more antibodies were cloned from flow sorted CD38+ cells from an eighth biopsy. Antigen characterization was performed using a combination of confocal microscopy, ELISA, screening protoarrays, immunoprecipitation and mass spectrometry. Serum IgG titers to the dominant antigen were determined in 48 LuN and 35 non-nephritic lupus samples using purified antigen-coated arrays. Autoantigen expression was localized by immunohistochemistry and immunofluorescence on normal and LuN kidney. Results Eleven of 25 antibodies reacted with cytoplasmic structures, four reacted with nuclei, and none with dsDNA. Vimentin was the only autoantigen identified by both mass spectrometry and by protoarray. Ten of the 11 anti-cytoplasmic TII antibodies directly bound vimentin. Vimentin was highly expressed by tubulointerstitial inflammatory cells, and tested TII antibodies preferentially bound inflamed tubulointerstitium. Finally, high-titers of serum anti-vimentin antibodies were associated with severe TII (p = 0.0001). Conclusion Vimentin, an antigenic feature of inflammation, is a dominant autoantigen targeted in situ in LuN TII. This adaptive autoimmune response likely feeds forward to worsen TII and renal damage.

The Pathogenesis and Therapeutic Implications of Tubulointerstitial Inflammation in Human Lupus Nephritis

“…These histological features suggest that interstitial B and T cell infiltrates are being selected in situ by locally occurring antigen. Consistent with this, sampling of expressed immunoglobulin repertoires from the tubulointerstitum has revealed local clonal expansion and ongoing somatic hypermutation 46, 50 . Analysis of the distribution of mutations in those regions of expressed antibodies containing the variable regions (Complementarity determining regions or CDRs) indicted that mutations arising from somatic hypermutation were being subsequently selected by antigen.…”

“…To identify the antigens driving in situ B cell selection, variable region heavy and light chain immunoglobulin pairs from clonally expanded B cell populations were cloned and expressed 50 . Remarkably, most of these antibodies, expressed from seven patients, were reactive with cytoplasmic, and not nuclear, antigens in HEp-2 cells.…”

Intrarenal activation of adaptive immune effectors is associated with tubular damage and impaired renal function in lupus nephritis

“…10 In a later publication, authors from the same group found that vimentin is overexpressed by mononuclear cells infiltrating the renal interstitium in lupus biopsies, and is a recurrent target of locally produced immunoglobulins. 44 Similarly, evaluation of the local T cell receptor repertoire is also indicative of a clonal expansion of a restricted population of T cells. 45 46 Local antigens, driving the proliferation of these T cells in the lupus kidney, were not identified yet.…”

T-cell receptor–HLA-DRB1 associations suggest specific antigens in pulmonary sarcoidosis

“…Renal inflammation is a frequent and severe manifestation of systemic lupus erythematosus, with tubulointerstitial inflammation (TII) as a common variant. Vimentin was recently shown to be the main targeted auto-antigen in TII [34]. An altered and increased expression of vimentin locally in the kidneys, as well as an association between high titres of serum anti-vimentin autoantibodies and disease severity, was observed in patients with TII, implicating both systemic and local autoimmunity.…”