Increased oxidative stress and apoptosis in acute puromycin aminonucleoside nephrosis

Abstract

Accumulating evidence demonstrates that oxidative stress is one of the underlying mechanisms to induce apoptosis in different biological systems. The aim of this study was to examine the simultaneous presence and correlation between oxidative stress events, apoptosis, apoptosis-associated proteins and monocyte/macrophage infiltration during the course of acute puromycin aminonucleoside nephrosis (PAN). To induce nephrosis, Sprague-Dawley rats were injected intraperitoneally with puromycin aminonucleoside and killed at weeks 1 and 2 of nephrosis. Controls represent animals injected with 0.9% saline solution. Kidney sections were homogenized to measure nitric oxide (NO), malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase activities by appropriate enzymatic and biochemical methods. Renal frozen sections were studied for superoxide anion (O(2) (-)) by a histochemical method, for apoptosis by TUNEL (terminal-deoxynucleotidyl-transferase-mediated dUTP- digoxigenin nick end labelling) and for apoptosis-associated protein expression and monocyte/macrophage infiltration by monoclonal antibodies. Increased renal apoptosis, p53, Bax, Bcl-2 accompanied by increased O(2) (-) and NO generation, lipid peroxidation (MDA) and monocyte/macrophage infiltration were found in nephrotic animals. Renal oxidative stress (O(2) (-), NO and MDA) was correlated with apoptosis, p53 expression, monocyte/macrophage cells and proteinuria. Anti-oxidant molecules (SOD and GSH) remained unchanged apart from a decreased activity of catalase which correlated with glomerular apoptosis. In conclusion, the close correlation between the presence of apoptosis and oxidative events confirms the role of oxidative stress in the apoptosis observed during PAN.

Dexamethasone Prevents Podocyte Apoptosis Induced by Puromycin Aminonucleoside

“…A recent study described that IGF-1 protected podocytes from etoposide-induced apoptosis and that Bad phosphorylation as well as the activation of the phosphatidylinositol 3Ј-kinase pathway were associated with the antiapoptotic effect (52). In this study, we showed that exposure of podocytes to PA increased levels of Bax, which is consistent with findings from previous in vivo studies in the PAN rat model of FSGS (48). Our data also showed that PA reduces the antiapoptotic protein Bcl-xL.…”

“…Furthermore, dexamethasone completely suppressed the upregulation of p53 induced by PA. Taken together, these results suggest that PA-induced podocyte apoptosis is p53 dependent and that dexamethasone may protect podocytes from PA-induced podocytes by inhibiting p53. Previous studies showed that p53 is increased in PAN rats in vivo (48,49). We recently described an increase in p53 in podocytes in experimental membranous nephropathy (50).…”

Pirfenidone inhibits macrophage infiltration in 5/6 nephrectomized rats

“…M1 macrophages exhibit proinflammatory properties, whereas, M2 macrophages promote fibrogenesis and tissue remodeling. Studies have shown that inhibition of macrophage infiltration reduces proteinuria and structural injury in models including antiglomerular basement disease, puromycin aminonucleoside nephrosis, and Heymann nephritis (8,31,41). It has been suggested that macrophage inhibition is likely to be an effective therapeutic approach in CKD treatment.…”

mTOR inhibition with temsirolimus causes acute increases in glomerular permeability, but inhibits the dynamic permeability actions of puromycin aminonucleoside

“…The PAN model has over the years become an experimental prototype of human minimal change disease and focal segmental glomerulosclerosis (39), and there is accumulating evidence that ROS generation and oxidative stress are main features of the pathogenesis of the glomerular barrier disruption induced by PAN (13,20,36,42,43,50). Hence, an increased production of ROS will activate TRPC6 Ca 2ϩ channels and intracellular Ca 2ϩ signaling (50) to increase glomerular permeability and to eventually produce DNA damage, cell cycle arrest, and thereby cell injury (32).…”