Long-Lasting Effects of Bacterial Lipopolysaccharide Promote Progression of Lupus Nephritis in NZB/W Mice

Abstract

Lupus prone NZB/W mice repeatedly exposed to bacterial lipopolysaccharide (LPS) develop enhanced polyclonal B cell activation and exacerbated nephritis by a mechanism that results in increased deposits of immunoreactants in kidneys without measurable impairment of mononuclear phagocyte function. In this paper, we investigate whether the referenced effects of LPS are reversible after withdrawal of LPS, or whether their persistence could contribute to progression of nephritis to chronicity. In NZB/W mice previously exposed to LPS, features of enhanced polyclonal B cell activation, more severe glomerulonephritis with tubulointerstitial involvement, increased deposits of immunoreactants in glomeruli, and altered protein excretion persisted 6 weeks after LPS was discontinued. Additionally, mononuclear phagocyte function, assessed through liver uptake of radiolabeled immune complexes, was found to be impaired. The results indicate that some of the effects of prior exposure to LPS may be partially reversible; however, they last long after LPS has been discontinued, and additional impairment of immune function develops together with permanent glomerular dysfunction, thereby contributing to progression of nephritis to chronicity.