Excreted urinary mediators in an animal model of experimental immune nephritis with potential pathogenic significance

Abstract

Objective. Currently, proteinuria is viewed as the earliest indicator of renal disease in immune-mediated nephritis. The objective of this study was to determine whether additional mediators may be excreted in the urine during immune-mediated nephritis, using an experimental model with a well-defined disease course.Methods. Urine samples from mice with antiglomerular basement membrane (anti-GBM) antibodyinduced experimental nephritis were screened using a focused immunoproteome array bearing 62 cytokines/ chemokines/soluble receptors. Molecules identified through this screening assay were validated using an enzyme-linked immunosorbent assay. One of these molecules was further evaluated for its pathogenic role in disease, using antibody-blocking studies.Results. Compared with B6 and BALB/c mice, in which moderately severe immune-mediated nephritis develops, the highly nephritis-susceptible 129/Sv and DBA/1 mice exhibited significantly increased urinary levels of vascular cell adhesion molecule 1 (VCAM-1), P-selectin, tumor necrosis factor receptor I (TNFRI), and CXCL16, particularly at the peak of disease. Whereas some of the mediators appeared to be serum derived early in the disease course, local production in the kidneys appeared to be an important source of these mediators later in the course of disease. Both intrinsic renal cells and infiltrating leukocytes appeared to be capable of producing these mediators. Finally, antibodymediated blocking of CXCL16 ameliorated experimental immune nephritis.Conclusion. These studies identified VCAM-1, P-selectin, TNFRI, and CXCL16 as a quartet of molecules that have potential pathogenic significance; the levels of these molecules are significantly elevated during experimental immune nephritis. The relevance of these molecules in spontaneous immune nephritis warrants investigation.

Elevated Urinary VCAM-1, P-Selectin, Soluble TNF Receptor-1, and CXC Chemokine Ligand 16 in Multiple Murine Lupus Strains and Human Lupus Nephritis

“…Hence, this represents the first report of elevated urinary sTNFR-1 in lupus nephritis. However, urinary TNFR-1 in murine and human lupus nephritis may be originating from the serum at least in part, based on our findings, consistent with our findings in the experimental anti-glomerular basement membrane (GBM) model (20).…”

“…Likewise, it has been suggested that glomerular disease may be amenable for therapy by blocking P-selectin (42). Based on our Ab blocking studies in the experimental anti-GBM nephritis model, CXCL16 may turn out to be yet another therapeutic target in nephritis (20). Finally, it remains to be seen whether the coordinate blocking of one or more of these molecules may offer therapeutic relief that is even more superior in lupus nephritis.…”

“…Finally, given the observation by ourselves and others (20) that at least some of these molecules may play critical roles in the pathogenesis of nephritis, they also represent potential targets for therapeutic intervention. Indeed, VCAM-1 has been suggested as a potential therapeutic target in inflammatory end-organ disease (26,27).…”

“…Second, these molecules are enriched in the urine, particularly in mice and patients with severe lupus nephritis, an observation that begs the question of whether these molecules are actually mediating the pathogenesis of nephritis. Third, we have recently demonstrated the pathogenic role of CXCL16 in experimental anti-GBM disease (20). Given these promising leads, more work needs to be done to elucidate the cellular origins of these molecules within the diseased kidneys, and to establish the degree to which these different molecules are required for renal disease to ensue in lupus.…”

“…This experimental model, which is induced by the administration of rabbit anti-glomerular Abs (17), is strain dependent (18,19). We recently noted that strains that developed more severe disease following the antiglomerular insult exhibited higher urinary levels of VCAM-1, P-selectin, sTNFR-1, and CXCL16 (20). Given that these molecules were previously observed to be generated at least in part in the kidneys and appeared to have pathogenic relevance, it is important to ascertain whether these molecules are also elevated in the urine during spontaneous lupus nephritis.…”