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Experimental crescentic glomerulonephritis (GN) is

Abstract. Macrophages are prominent participants in crescentic glomerulonephritis (GN) and have been suggested to be the major source of TNF in this cell-mediated form of glomerular inflammation. Intrinsic renal cells also have the capacity to produce TNF. For dissecting the contribution of local versus bone marrow (BM)-derived TNF in inflammatory renal injury, TNF chimeric mice were created by transplanting normal wildtype (WT) BM into irradiated TNF-deficient recipients (WT3 TNF Ϫ/Ϫ chimeras) and vice versa (TNF Ϫ/Ϫ 3 WT chimeras). A model of crescentic GN induced by an intravenous injection of sheep anti-murine glomerular basement membrane antibody was studied in WT mice, mice with complete TNF deficiency (TNFϪ/Ϫ), and chimeric mice. Crescentic GN was attenuated in TNFϪ/Ϫ mice with fewer crescents (crescents, 13.7 Ϯ 1.7% of glomeruli) and reduced functional indices of renal injury (serum creatinine, 15.2 Ϯ 0.8 mol/L). Similar protection (crescents, 14.3 Ϯ 1.9% of glomeruli; serum creatinine, 18.9 Ϯ 1.1 mol/L) was observed in chimeric mice with intact BM but absent renal-derived TNF (WT3 TNF Ϫ/Ϫ chimeras), suggesting a minor contribution of infiltrating leukocytes to TNF-mediated renal injury. Chimeric mice with TNFdeficient leukocytes but intact intrinsic renal cell-derived TNF (crescents, 20.5 Ϯ 2.0% of glomeruli; serum creatinine, 21.6 Ϯ 1.4 mol/L) developed similar crescentic GN to WT mice (crescents, 22.3 Ϯ 1.4% of glomeruli; serum creatinine, 24.8 Ϯ 1.9 mol/L). Cutaneous delayed-type hypersensitivity after subdermal challenge with the nephritogenic antigen was attenuated in the absence of BM cell-derived TNF but unaffected in WT3 TNF Ϫ/Ϫ chimeric mice. These studies suggest that intrinsic renal cells are the major cellular source of TNF contributing to inflammatory injury in crescentic GN.

Many adhesion molecule pathways have been invoked as mediating leukocyte recruitment during immune complex-induced inflammation. However the individual roles of these molecules have not been identified via direct visualization of an affected microvasculature. Therefore, to identify the specific adhesion molecules responsible for leukocyte rolling and adhesion in immune complex-dependent inflammation we used intravital microscopy to examine postcapillary venules in the mouse cremaster muscle. Wild-type mice underwent an intrascrotal reverse-passive Arthus model of immune complex-dependent inflammation and subsequently, leukocyte-endothelial cell interactions and P- and E-selectin expression were assessed in cremasteric postcapillary venules. At 4 hours, the reverse-passive Arthus response induced a significant reduction in leukocyte rolling velocity and significant increases in adhesion and emigration. P-selectin expression was increased above constitutive levels whereas E-selectin showed a transient induction of expression peaking between 2.5 to 4 hours and declining thereafter. While E-selectin was expressed, rolling could only be eliminated by combined blockade of P- and E-selectin. However, by 8 hours, all rolling was P-selectin-dependent. In contrast, inhibition of vascular cell adhesion molecule-1 had a minimal effect on leukocyte rolling, but significantly reduced both adhesion and emigration. These observations demonstrate that immune complex-mediated leukocyte recruitment in the cremaster muscle involves overlapping roles for the endothelial selectins and vascular cell adhesion molecule-1.