Lack of endothelial nitric oxide synthase aggravates murine accelerated anti-glomerular basement membrane glomerulonephritis

Nitric oxide (NO) radicals generated by endothelial nitric oxide synthase ( eNOS) are involved in the regulation of vascular tone. In addition, NO radi cals derived from eNOS inhibit platelet aggregation and leukocyte adhesion to the endothelium and, thus, may have anti-inflammatory effects. To study the role of eNOS in renal inflammation, the development of accelerated anti -glomerular basement membrane (GBM) glomerulonephritis was examined in mice lacking a functional gene for eNOS and compared with wild-type (WT) C57BL/ B6j mice. WT C57BL/6j mice (n = 12) and eNOS knockout (-/-) mice (n = 12) w ere immunized intraperitoneally with sheep IgG (0.2 mg in complete Freund's adjuvant), At day 6.5 after immunization, mice received a single i.v. inje ction of sheep anti-mouse GBM (1 mg in 200 mu l PBS). Mice were sacrificed at day 1 and 10 after induction of the disease. All WT mice survived until day 10, whereas 1 eNOS-/- mouse died and 2 more became moribund, requiring sacrifice. At day 10, eNOS-/- mice had higher levels of blood urea nitrogen than WT mice (P < 0.02), although proteinuria was comparable. Immunofluore scence microscopy documented similar IgG deposition in both WT and eNOS-/- mice,but eNOS-/- mice had more extensive glomerular staining for fibrin at day 10 (P < 0.007), At day 10, light microscopy demonstrated that eNOS-/- m ice had more severe glomerular thrombosis (P < 0.003) and influx of neutrop hils (P < 0.006), but similar degrees of overall glomerular endocapillary h ypercellularity and crescent formation. In conclusion, accelerated anti-GBM glomerulonephritis is severely aggravated in eNOS-/- mice, especially with respect to glomerular capillary thrombosis and neutrophil infiltration, Th ese results indicate that NO radicals generated by eNOS play a protective r ole during renal inflammation.