Long-term effect of Heme oxygenase (HO)-1 induction in glomerular immune injury PRASUN K. DATTA, PU DUANN, and ELIAS A. LIANOS PHILADELPHIA, PENNSYLVANIA AND NEW BRUNSWICK, NEW JERSEY In a rat model of macrophage-dependent glomerular immune injury induced by administration of antibody against the glomerular basement membrane (anti- GBM), the authors assessed the anti-proteinuric effect of Heme Oxygenase-1 (HO-1) induction. Rats received anti-GBM antibody alone, anti-GBM antibody and treatment with the HO-1 inducer, hemin, or non-immune serum (controls). Urine protein, creatinine, and nitrite/nitrate excretion were measured on days 5, 7, and 14 after administration of the anti-GBM antibody. In hemin-treated ani- mals with anti-GBM antibody-induced immune injury, HO-1 immunolocalized in macrophages infiltrating glomeruli and in tubular epithelial cells. In these ani- mals, proteinuria was decreased. There was also a decrease in blood urea nitrogen (BUN) levels without a change in serum creatinine or systemic blood pressure. The observations establish the anti-proteinuric effect of hemin induc- tion. This effect could be mechanistically linked to blunting of the ability of infiltrating macrophages to cause injury or to changes in tubular handling of filtered protein. (J Lab Clin Med 2006;147:150 –155) Abbreviations: ABC = avidin biotin complex; BP = blood pressure; BSA = bovine serum albumin; BUN = blood urea nitrogen; CO = carbon monoxide; DAB = diaminobenzidine tetrahydrochloride; DTH = delayed-type hypersensitivity; GBM = glomerular basement membrane; GFR = glomerular filtration rate; HO-1 = Heme oxygenase-1; iNOS = inducible nitric oxide synthetase; NO = nitric oxide; SD = standard deviation; Th1 = T helper cell 1; TNF= tumor necrosis factor-alpha; U alb = urine albumin; Uc = urine creatinine I n a rat model of glomerular injury induced by antibody against the GBM, the authors previously demonstrated that treatment with the HO-1 in- ducer, hemin, attenuated proteinuria while it reduced activity of the iNOS. 1 These studies were performed at very early stages (24 h) of injury when upregula- tion of glomerular iNOS (a heme containing protein) expression and enzyme activity occurs. 1,2 It was pro- posed that the beneficial effect of HO-1 induction on proteinuria could be linked to the reduction of iNOS activity, thereby reducing NO production. iNOS-cat- alyzed NO production can be sustained and of high output, and NO can cause cell injury either on its own 3 or by interacting with superoxide (O 2 - ) to form the potent and relatively stable oxidant peroxyni- trite. 4 However, the upregulation of iNOS expression and activity in glomeruli after immune injury is short-lived; although clearly detectable at 24 – 48 h after onset of injury, it becomes barely detectable thereafter. 2,5 The effect of HO-1 induction on pro- teinuria when glomerular iNOS expression is no longer increased is unknown. These studies were designed to address this question and show that long- term HO-induction using treatment with the HO-1 From the Temple University Center for Neurovirology and Cancer Biology, Philadelphia, Pennsylvania; and Department of Medicine/ Division of Nephrology, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, New Jersey. Submitted for publication September 7, 2005; revision submitted November 11, 2005; accepted for publication November 11, 2005. Reprint requests: Elias A. Lianos, MD, PhD, UMDNJ-Robert Wood Johnson Medical School, Department of Medicine/Division of Ne- phrology, P.O. Box 19-MEB 412, New Brunswick, N.J. 08903-0019; e-mail: lianosea@umdnj.edu. 0022-2143/$ – see front matter © 2006 Mosby, Inc. All rights reserved. doi:10.1016/j.lab.2005.11.009 150