Preprint Defective B cell tolerance in SLE lymph nodes underpins VH4-34 "clonal damnation" and PD-1+TOX+ autoreactive B cells expansion., 2026, Faliti et al.

[SNT Gatchaman]

Defective B cell tolerance in SLE lymph nodes underpins VH4-34 "clonal damnation" and PD-1+TOX+ autoreactive B cells expansion.

Spoiler: Authors

Caterina E Faliti; Midushi Ghimire; Melissa Garcia Vega; Rachel C Watermeier; Amanda R Callahan; Julia burke; Olivia Posadas; Ashish K Mishra; Surender Khurana; Victor Greiff; Christopher D Scharer; John M Lindner; Rodney G King; Mary Newell; Arezou Khosroshahi; Frances Eun-Hyung Lee; Ignacio Sanz

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease driven by uncensored B and T cell autoreactivity. Understanding this pathogenic process has been hampered by lack of studies of secondary lymphoid organs in human SLE.

Using minimally invasive lymph node fine needle aspirates (LN-FNAs), we profiled tissue-resident immune cells from 59 SLE patients and 34 healthy controls through high-dimensional 43-color flow cytometry, antigen-specific tetramer probing, and sc-RNA sequencing with paired VH/VL repertoire analysis.

Our findings reveal hyperactive lymph node immunity in SLE characterized by spontaneous germinal center (GC) activation, plasma cell accumulation enriched in mature CD19- and CD138+ antibody-secreting cells, and increased frequencies of both GC-TFH and PD-1+CXCR5- T extra-follicular helper cells. SLE lymph nodes harbored large oligoclonal B cell families with altered isotype usage, dominated by IgG1 and IgG4.

Critically, self-reactive 9G4+ and Ro60+ B cells showed defective tolerance checkpoint control, accumulating in activated naive, GC, and plasma cell compartments with distinctive PD-1+Tox+ expression absent in viral-specific responses. Single-cell repertoire analysis revealed VH4-34 clones in SLE BGC and BPC, that in contrast to HD, had not experienced clonal redemption. Instead, SLE VH4-34 clones displayed low somatic hypermutation and preserved the AVY hydrophobic patch associated with autoreactivity. Monoclonal antibody testing confirmed that unmutated AVY+ VH4-34 clones retained polyreactivity against naive B cells, apoptotic cells, and multiple self-antigens.

Together, these results define "clonal damnation" as a key mechanism in SLE whereby autoreactive VH4-34 clones of pathogenic potential escape tolerance checkpoints, expand in germinal centers, and differentiate into tissue plasma cells while preserving germline-encoded self-reactivity. Combined, our study defines critical mechanisms of tolerance breakdown in lupus pathogenesis.

Web | DOI | PDF | Preprint: MedRxiv | Open Access

 

[SNT Gatchaman]

Selected quotes from discussion —

Cellular therapies have recently shown remarkable efficacy in SLE, suggesting that deep B cell depletion and immune resetting may be critical for achieving long-term remission and drug-free states. […] Notably, a recent proof-of-concept study proposed the use of VH 4-34 targeted CAR-T (CAR4-34) to specifically target self-reactive B cells in lupus and cancer, reducing the risk of antigen-negative escape observed at times with CAR-19.

Alongside hyperactive germinal centers, SLE LNs hosted a greater number of terminally differentiated plasma cells. These data are consistent with the reported expansion of blood-circulating BPC in SLE with a more mature phenotype, and might suggest that LNs could represent a niche for the accumulation of tissue-resident plasma cells with pathogenic potential and contribution to tissue damage.

We observed a larger oligoclonal expansion in SLE LN B cells, with altered isotype usage and a greater representation of IgG4-bearing BCRs. While pathogenic IgG4 autoantibodies are well reported in various autoimmune conditions, such as IgG4-RD, Pemphigus, and Myasthenia gravis IgG4 B cells are not usually detected in studies with peripheral blood. We now showed that IgG4 B cells are detectable with significant frequencies in lupus LNs and associated with autoreactivity.

Overall, our study revealed how two unrelated lupus antigens escaped B cell tolerance and progressed unimpeded in the GC [Germinal Centre] and PC [Plasma Cell] compartments.

While the exact mechanism of regulation of those PD-1+/hi Tox +/hi B cells in SLE still remains to be elucidated, we propose that chronic autoantigen exposure and sustained BCR signaling might be responsible for this mechanism and thus distinguish the selection of self-reactive B cells in SLE when compared to both HD-reactive B cells as well as anti-viral B cells

In healthy conditions, VH 4-34 antibodies are regulated by process of clonal redemption and might be important for their participation to protective immune responses, such as anti-microbial or anti-viral responses

…suggesting that the mechanism of self-reactive clonal redemption might be at fault in autoimmune settings, and instead progress unimpeded into maturation and generation of autoreactive plasma cells with pathogenic potentials. We provided original evidence showing that B cell selection and aberrant affinity maturation processes are responsible for self reactive clonal escape to tolerance checkpoint in the BGC, with consequent accumulation of mutations in the BPC. This mechanism, hereby referred to as “clonal damnation”, proposes a system where normal selection of self-reactive clones of the VH 4-34 family against self or “clonal redemption” reported in healthy individuals, is faulty in SLE.

progressive maturation in B cell compartments, and accumulation of somatic hypermutations, favor the persistence of auto- and polyreactive clones that escape tolerance checkpoints, and reside in GC and PC compartments, in which progressive accumulation of mutations failed to eliminate self-reactivity and instead preserved – or even reinforced – it. Noteworthy, somatic hypermutations appear to be critical in the VH 4-34 selection process

These data support recent evidence in human viral infections where chronic exposure to SARS-CoV2 induced autoimmune-like symptoms that persisted even after viral clearance. Notably, one of the viral antigens strongly recognized by our SLE mAbs was EBNA1, a critical component of the Epstein-Barr virus (EBV) often reported in association with SLE. This study provides a mechanistic explanation that may underly this association.

 

[Jonathan Edwards]

I am not sure how much this takes forward the VH4-34 story that both Jo Cambridge and Ignaci Sanz were interested in way back. It seems a bit like 'Hey all you guys impressed by CR-T cells - well remember that VH4-34 stuff we were doing 25 years ago - it could be relevant and we are still doing the same stuff.' Sanz's group were interested in using ritux in lupus in 2000 after we did the first study in RA but in essence Maria beat them to it.

And it seems that they may still be stuck with the idea of autoimmunity being triggered by infection and molecular mimicry:
"These data support recent evidence in human viral infections where chronic exposure to SARS-CoV2 induced autoimmune-like symptoms that persisted even after viral clearance."