Antiapoptotic properties of erythropoiesis-stimulating proteins in models of cisplatin-induced acute kidney injury

Abstract

Erythropoietin (Epo) induces erythrocytosis by suppressing erythroid progenitor cell apoptosis through the Janus-activated kinase-signal transducers and activators of transcription (JAK-STAT) pathway. Since apoptosis contributes to cisplatin (CP)-induced nephrotoxicity and Epo receptors (EpoR) are expressed in the kidney, we examined the role of antiapoptosis in recombinant human erythropoietin (rHuEpo)-mediated renal protection. In human renal proximal tubular epithelial (RPTE) cells in culture, rHuEpo, but not inactive rHuEpo (I-rHuEpo), the receptor-binding sites of which are mutated, caused a significant reduction in CP-induced apoptosis at > or = 100 U/ml. rHuEpo, but not I-rHuEpo, increased STAT5 and Akt/PKB phosphorylation, demonstrating functional EpoR expression on RPTE cells. Furthermore, the JAK2 inhibitor tyrphostin AG-490 attenuated rHuEpo protection, suggesting a role of the JAK-STAT pathway in rHuEpo-mediated antiapoptosis. In rats, intravenous administration of 5,000 U/kg rHuEpo, but not an equivalent peptide mass of I-rHuEpo, before a single 5.5 mg/kg iv injection of CP, significantly increased hematocrit (Hct) and reduced the CP-induced increase in serum creatinine. Serum creatinine on day 4 was 3.4 +/- 0.3, 1.9 +/- 0.3, and 3.5 +/- 0.4 mg/dl in the CP, CP + rHuEpo, and CP + I-rHuEpo groups, respectively. Similarly, darbepoietin-alpha (DA), a hyperglycosylated analog of rHuEpo with prolonged in vivo activity when injected at 25 microg/kg iv before CP, significantly increased Hct and reduced serum creatinine. Renal clearance studies based on glomerular filtration rate and renal blood flow confirmed the significant renal protection by DA against CP. Tubular apoptosis and necrosis were significantly reduced in the kidneys of the CP + DA vs. the CP + saline group. Moreover, the equalization of Hct by venesection did not abrogate the DA-mediated renal protection. Administration of DA 48 h after CP injection also conferred significant renal protection. Thus our experiments confirm a role for erythropoiesis-stimulating proteins, including the new analog DA, in limiting CP-induced nephrotoxicity and suggest that antiapoptosis via the Epo-EpoR interaction is an important mechanism for renal protection.

Cardioprotection by a nonerythropoietic, tissue-protective peptide mimicking the 3D structure of erythropoietin

“…Recent studies have demonstrated that EPO and TPCs, nonerythropoietic derivatives of EPO, protect a wide variety of tissues (21)(22)(23)(24), including the heart, from I/R injury (16)(17)(18). These protective effects of EPO and TPCs have been shown in part to be mediated by preventing apoptosis (16)(17)(18)24). Our data are consistent with previous findings observed for EPO and TPCs and confirm the antiapoptotic effect of HBSP on cardiomyocytes.…”

“…This effect is comparable with that observed for EPO on a molar basis, and similarly obtained regardless of timing of treatment. Recent studies have demonstrated that EPO and TPCs, nonerythropoietic derivatives of EPO, protect a wide variety of tissues (21)(22)(23)(24), including the heart, from I/R injury (16)(17)(18). These protective effects of EPO and TPCs have been shown in part to be mediated by preventing apoptosis (16)(17)(18)24).…”

Erythropoietin-induced upregulation of endothelial nitric oxide synthase but not vascular endothelial growth factor prevents musculocutaneous tissue from ischemic damage

“…11 Our results showed that administration of EPO significantly decreased the number of apoptotic cells when compared with untreated flaps and animals receiving L-Name only. This is in line with a previous study of our group, in which we could show that apoptotic cell death was significantly reduced even if EPO was administered only after flap elevation.…”

“…Recent findings revealed tissue-protective properties of EPO independent of its hematopoietic properties in a variety of organ systems suffering from ischemia, such as the heart, 5 brain, 6,7 liver, 8 kidney 9 and the striated muscle. 10 EPO initiates a multitude of EPO receptor-dependent and -independent cellular pathways, including the induction of anti-apoptotic genes 11 and anti-inflammatory molecules, 12 the increase of vascular endothelial growth factor (VEGF), as well as the production of vasodilative molecules such as nitric oxide (NO). 13 NO is an enzymatic product from L-arginine that mediates numerous biological actions through the activation of cyclic guanosine monophosphate, which inhibits intracellular calcium release and induces smooth muscle relaxation.…”

Suppression of Coronary Atherosclerosis by Helix B Surface Peptide, a Nonerythropoietic, Tissue-Protective Compound Derived from Erythropoietin

“…Recent work has shown that EPO and its nonerythropoietic derivatives, including HBSP, provide tissue-protective effects in a wide variety of tissues, in part by inhibiting apoptosis and by counteracting proinflammatory cytokines such as TNF-α (13,(22)(23)(24)(25)(26). Consistent with these observations, our data obtained from the in vitro experiments clearly demonstrate that HBSP, as well as EPO, reduces HUVEC apoptosis and THP-1 production of TNF-α and MMP-9 induced by CRP, a direct mediator of atherosclerosis (16,(19)(20)(21).…”