4-hydroxy-2-nonenal and Glomerulonephritis

Angiotensin-converting enzyme (ACE) inhibitors ameliorate the progression of renal disease. In combination with vitamin D receptor activators, they provide additional benefits. In the present study, uremic (U) rats were treated as follows: U+vehicle (UC), U+enalapril (UE; 25 mg/l in drinking water), U+paricalcitol (UP; 0.8 μg/kg ip, 3 × wk), or U+enalapril+paricalcitol (UEP). Despite hypertension in UP rats, proteinuria decreased by 32% vs. UC rats. Enalapril alone, or in combination with paricalcitol, further decreased proteinuria (≈70%). Glomerulosclerosis and interstitial infiltration increased in UC rats. Paricalcitol and enalapril inhibited this. The increase in cardiac atrial natriuretic peptide (ANP) seen in UC rats was significantly decreased by paricalcitol. Enalapril produced a more dramatic reduction in ANP. Renal oxidative stress plays a critical role in inflammation and progression of sclerosis. The marked increase in p22(phox), a subunit of NADPH oxidase, and decrease in endothelial nitric oxide synthase were inhibited in all treated groups. Cotreatment with both compounds inhibited the uremia-induced increase in proinflammatory inducible nitric oxide synthase (iNOS) and glutathione peroxidase activity better than either compound alone. Glutathione reductase was also increased in UE and UP rats vs. UC. Kidney 4-hydroxynonenal was significantly increased in the UC group compared with the normal group. Combined treatment with both compounds significantly blunted this increase, P < 0.05, while either compound alone had no effect. Additionally, the expression of Mn-SOD was increased and CuZn-SOD decreased by uremia. This was ameliorated in all treatment groups. Cotreatment with enalapril and paricalcitol had an additive effect in increasing CuZn-SOD expression. In conclusion, like enalapril, paricalcitol alone can improve proteinuria, glomerulosclerosis, and interstitial infiltration and reduce renal oxidative stress. The effects of paricalcitol may be amplified when an ACE inhibitor is added since cotreatment with both compounds seems to have an additive effect on ameliorating uremia-induced changes in iNOS and CuZn-SOD expression, peroxidase activity, and renal histomorphometry.

Topics: Aldehydes; Angiotensin-Converting Enzyme Inhibitors; Animals; Atrial Natriuretic Factor; Enalapril; Ergocalciferols; Female; Glomerulonephritis; Kidney; NADPH Oxidases; Nitric Oxide Synthase Type II; Oxidative Stress; Proteinuria; Rats; Receptors, Calcitriol; Superoxide Dismutase; Uremia

In glomerulonephritis (GN), an overload of free fatty acids (FFA) bound to albumin in urinary protein may induce oxidative stress in the proximal tubules. Human liver-type fatty acid-binding protein (hL-FABP) expressed in human proximal tubules, but not rodents, participates in intracellular FFA metabolism and exerts anti-oxidative effects on the progression of tubulointerstitial damage. We examined whether tubular enhancement of this anti-oxidative action modulates the progression of glomerular damage in immune-mediated GN in hL-FABP chromosomal gene transgenic (Tg) mice.. Anti-glomerular basement membrane antibody-induced glomerulonephritis (anti-GBM GN) was induced in Tg and wild-type mice (WT). Proteinuria, histopathology, polymorphonuclear (PMN) influx, expression of tubulointerstitial markers for oxidative stress 4-hydroxy-2-Nonenal (HNE) and fibrosis (α-smooth muscle actin), proximal tubular damage (Kim-1), Peroxisome Proliferator-Activated Receptor γ (PPAR γ) and inflammatory cytokines [Monocyte Chemotactic Protein-1, tumor necrosis factor-alpha (TNF-α) and Transforming growth factor beta (TGF-β)] were analyzed. The mice were also treated with an angiotensin type II receptor blocker (ARB).. The urinary protein level in Tg mice decreased significantly during the acute phase (~Day 5). Tg mice survived for a significantly longer time than WT mice, with an attenuation of tubulointerstitial damage score and expression of each tubulointerstitial damage marker observed at Day 7. Expression of inflammatory cytokines on Day 7 was higher in WT mice than Tg mice and correlated strongly with PPARγ expression in WT mice, but not in Tg mice. Interestingly, Tg mice showed insufficient PMN influx at 3 and 6 h, with simultaneous elevation of urinary L-FABP and reduction in HNE expression. The two strains of mice showed different types of glomerular damage, with mild mesangial proliferation in Tg mice and severe endothelial swelling with vascular thrombosis in WT mice. The glomerular damage in Tg mice was improved by administration of an ARB.. The present experimental model suggests that tubular enhancement of L-FABP may protect mice with anti-GBM GN from progression of both tubulointerstitial and glomerular injury.

Topics: Aldehydes; Angiotensin Receptor Antagonists; Animals; Autoantibodies; Blotting, Western; Chemokine CCL2; Cysteine Proteinase Inhibitors; Cytokines; Fatty Acid-Binding Proteins; Fatty Acids, Nonesterified; Female; Glomerulonephritis; Humans; Inflammation; Kidney Tubules, Proximal; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Transgenic; Nephritis, Interstitial; Oxidative Stress; PPAR gamma; Proteinuria; Real-Time Polymerase Chain Reaction; RNA, Messenger; Survival Rate; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

Aging is characterized by renal functional and structural abnormalities resembling those observed in diabetes. These changes have been related to the progressive accumulation of advanced glycation end-products (AGEs) and cumulative oxidative stress occurring in both conditions. We previously reported that galectin-3 ablation is associated with increased susceptibility to diabetes- and AGE-induced glomerulopathy, thus indicating a protective role of galectin-3 as an AGE receptor. To investigate the role of the AGE/AGE receptor pathway in the pathogenesis of age-related renal disease, we evaluated the development of glomerular lesions in aging galectin-3 knockout (KO) vs. wild-type (WT) mice and their relation to the increased AGE levels and oxidative stress characterizing the aging process. KO mice showed significantly more pronounced age-dependent increases in proteinuria, albuminuria, glomerular sclerosis, and glomerular and mesangial areas, starting at 18 mo, as well as renal extracellular matrix mRNA and protein expression, starting at 12 mo vs. age-matched WT mice. Circulating and renal AGEs, plasma isoprostane 8-epi-PGF2alpha levels, glomerular content of the glycoxidation and lipoxidation products N(epsilon)-carboxymethyllysine and 4-hydroxy-2-nonenal, and renal nuclear factor-kappaB activity also increased more markedly with age in KO than WT mice. AGE levels correlated significantly with renal functional and structural parameters. These data indicate that aging galectin-3 KO mice develop more pronounced changes in renal function and structure than coeval WT mice, in parallel with a more marked degree of AGE accumulation, oxidative stress, and associated low-grade inflammation, thus supporting the concept that the AGE/AGE receptor pathway is implicated in age-related renal disease.

Topics: Age Factors; Aging; Aldehydes; Animals; Body Weight; Dinoprost; Extracellular Matrix; Galectin 3; Glomerulonephritis; Glycation End Products, Advanced; Kidney Glomerulus; Lysine; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oxidative Stress; Receptor for Advanced Glycation End Products; Receptors, Immunologic; RNA, Messenger; Transforming Growth Factor beta; Transforming Growth Factor beta1

Passive Heymann nephritis (PHN) is a model of human membranous nephropathy that is characterized by formation of granular subepithelial immune deposits in the glomerular capillary wall which results in complement activation. This is causally related to damage of the filtration barrier and subsequent proteinuria. The local accumulation of injurious reactive oxygen species (ROS) is a major effector mechanism in PHN. ROS may induce tissue damage by initiating lipid peroxidation (LPO). In turn, this leads to adduct formation between breakdown products of LPO with structural proteins, such as formation of malondialdehyde (MDA) or 4-hydroxynonenal-lysine adducts. To examine the role of LPO in the development of proteinuria we have localized MDA and 4-hydroxynonenal-lysine adducts in glomeruli of PHN rats by immunofluorescence microscopy, using specific monoclonal antibodies. By immunogold electron microscopy, MDA adducts were localized to cytoplasmic vesicles and cell membranes of glomerular epithelial cells, to the glomerular basement membrane (GBM), and also to immune deposits. Type IV collagen was specifically identified as being modified by MDA adducts, using a variety of techniques. Collagenase pretreatment of GBM extracts indicated that the NC-1 domain of type IV collagen was a site of adduct formation. When LPO was inhibited by pretreatment of PHN rats with the antioxidant probucol, proteinuria was reduced by approximately 85%, and glomerular immunostaining for dialdehyde adducts was markedly reduced, even though the formation of immune deposits was not affected. By contrast, lowering of the serum cholesterol levels had no influence on the development of proteinuria. These findings are consistent with the premise that ROS-induced glomerular injury in PHN involves LPO and that this results not only in damage of cell membranes but in modification of type IV collagen in the GBM as well. The close temporal correlation of the occurrence of LPO with proteinuria and the ability of probucol to inhibit proteinuria support a causal role for LPO in the the alteration of the glomerular permselectivity which results in proteinuria.

Topics: Aldehydes; Animals; Anticholesteremic Agents; Antigen-Antibody Complex; Basement Membrane; Cholesterol; Collagen; Disease Models, Animal; Epithelial Cells; Glomerulonephritis; Kidney Glomerulus; Lipid Peroxidation; Lovastatin; Lysine; Male; Malondialdehyde; Probucol; Proteinuria; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Simvastatin