Neutrophils Slow Disease Progression in Murine Lupus via Modulation of Autoreactive Germinal Centers.

Neutrophils are well characterized as mediators of peripheral tissue damage in lupus, but it remains unclear whether they influence loss of self-tolerance in the adaptive immune compartment. Lupus neutrophils produce elevated levels of factors known to fuel autoantibody production, including IL-6 and B cell survival factors, but also reactive oxygen intermediates, which can suppress lymphocyte proliferation. To assess whether neutrophils directly influence the progression of autoreactivity in secondary lymphoid organs (SLOs), we characterized the localization and cell-cell contacts of splenic neutrophils at several stages in the progression of disease in the NZB/W murine model of lupus. Neutrophils accumulate in SLO over the course of lupus progression, preferentially localizing near T lymphocytes early in disease and B cells with advanced disease. RNA sequencing reveals that the splenic neutrophil transcriptional program changes significantly over the course of disease, with neutrophil expression of anti-inflammatory mediators peaking during early-stage and midstage disease, and evidence of neutrophil activation with advanced disease. To assess whether neutrophils exert predominantly protective or deleterious effects on loss of B cell self-tolerance in vivo, we depleted neutrophils at different stages of disease. Neutrophil depletion early in lupus resulted in a striking acceleration in the onset of renal disease, SLO germinal center formation, and autoreactive plasma cell production. In contrast, neutrophil depletion with more advanced disease did not alter systemic lupus erythematosus progression. These results demonstrate a surprising temporal and context-dependent role for neutrophils in restraining autoreactive B cell activation in lupus.