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Sepsis remains the most important cause of acute kidney injury (AKI) in critically ill patients and is an independent predictor of poor outcome. The administration of lipopolysaccharide (LPS) to animals reproduces most of the clinical features of sepsis, including AKI, a condition associated with renal cellular dysfunction and apoptosis. Erythropoietin (EPO) is a well known cytoprotective multifunctional hormone, which exerts anti-inflammatory, anti-oxidant, anti-apoptotic and angiogenic effects in several tissues. The aim of this study was to evaluate the underlying mechanisms of EPO renoprotection through the expression of the EPO receptor (EPO-R) and the modulation of the intrinsic apoptotic pathway in LPS-induced AKI. Male inbred Balb/c mice were divided in four experimental groups: Control, LPS (8 mg/kg i.p.), EPO (3000 IU sc) and LPS+EPO. Assessment of renal function, histological examination, TUNEL in situ assay, immunohistochemistry and Western blottings of caspase-3, Bax, Bcl-xL, EPO-R and Cytochrome c were performed at 24h post treatment. LPS+EPO treatment significantly improved renal function and ameliorated histopathological injury when compared to the LPS treated group. Results showed that EPO treatment attenuates renal tubular apoptosis through: (a) the overexpression of EPO-R in tubular interstitial cells, (b) the reduction of Bax/Bcl-xL ratio, (c) the inhibition Cytochrome c release into the cytosol and (d) the decrease of the active caspase-3 expression. This study suggests that EPO exerts renoprotection on an experimental model of LPS-induced AKI. EPO induced renoprotection involves an anti-apoptotic effect through the expression of EPO-R and the regulation of the mitochondrial apoptotic pathway., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

The effect of a single dose of cyclophosphamide (CY, 150 mg/kg i.p.) on the erythropoiesis using an "in vivo" murine model in a time course protocol (0-10 days) was studied through several experimental approaches. Total and differential bone marrow cellularities, apoptosis (TUNEL assays), bone marrow hematopoietic architecture (scanning electronic microscopy), proliferation (DNA assay), BM erythroid progenitors growth (semisolid clonogenic assays) and protein expressions for erythroid commitment and survival: erythropoietin receptor (EPO-R), Bcl-x(L), Bax (immunoblottings) were performed on the scheduled days. Most of the experiences were conducted comparing spontaneous with human recombinant (hr EPO) "ex vivo" stimulated bone marrow (BM) cells. Erythropoiesis was extremely affected by CY. Maximum apoptosis, minimal cellularities and severe disturbances of BM niche were noticed on the second day. During spontaneous recovery post-CY; EPO-R was expressed between 4 and 5 days. Following BM cells "ex vivo" hr EPO stimulation (2U/ml) EPO-R was expressed throughout the study except the period between the first and fourth day. Bax was noticeable all along the experience with and without hr EPO stimulation. Bcl-x(L) was barely detectable without hr EPO, but its expression showed a gradual enhancement from the fifth day onwards in hr EPO stimulated cells. This fact might be related to the end of the erythroid inhibitory stage and to the recovery of BM EPO-dependent proliferation between the fourth and fifth day, and the further recuperation of BFU-E and CFU-E colonies on days 6 and 7 post-CY, respectively. These findings suggest that the proliferation and differentiation of erythroid progenitor cells after the acute early injury inflicted by CY, is associated with changes in EPO-R expression during spontaneous recovery in this particular experimental system.