The most prevalent severe manifestation of systemic lupus erythematosus (SLE) is nephritis which is characterized by immune complex deposition, inflammation, and scarring in both glomeruli and in the tubulointerstitium. Numerous studies indicate that glomerulonephritis results from a systemic break in B cell tolerance resulting in the local deposition of immune complexes containing antibodies reactive with ubiquitous self-antigens. However, the pathogenesis of SLE tubulointerstitial disease is not known. Herein, we demonstrate that in over half of a cohort of 68 lupus nephritis biopsies, the tubulointerstitial infiltrate was organized into either well-circumscribed T:B cell aggregates or germinal centers (GCs) containing follicular dendritic cells. Sampling of the in situ expressed immunoglobulin repertoire revealed that both histological patterns were associated with intrarenal B cell clonal expansion and ongoing somatic hypermutation. However, in the GC histology the proliferating cells were CD138−CD20+ centroblasts while in T:B aggregates, they were CD138+CD20low/− plasmablasts. The presence of either GCs or T:B aggregates was strongly associated with tubular basement membrane immune complexes. These data implicate tertiary lymphoid neogenesis in the pathogenesis of lupus tubulointerstitial inflammation.

These data implicate the Th17 axis and specifically IL-23 as mediators of more severe disease in AAV. Their persistence despite conventional treatment may contribute to high relapse rates.

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.

Percutaneous PD catheter insertion was associated with a very low complication rate and high primary success rate, and was highly efficient in use of resources and avoided the need for general anaesthesia.