Pigment epithelium-derived factor protects retinal ganglion cells

BACKGROUND: Retinal ganglion cells (RGCs) are responsible for the transmission of visual signals to the brain. Progressive death of RGCs occurs in glaucoma and several other retinal diseases, which can lead to visual impairment and blindness. Pigment epithelium-derived factor (PEDF) is a potent antiangiogenic, neurotrophic and neuroprotective protein that can protect neurons from a variety of pathologic insults. We tested the effects of PEDF on the survival of cultured adult rat RGCs in the presence of glaucoma-like insults, including cytotoxicity induced by glutamate or withdrawal of trophic factors. RESULTS: Cultured adult rat RGCs exposed to glutamate for 3 days showed signs of cytotoxicity and death. The toxic effect of glutamate was concentration-dependent (EC(50 )= 31 μM). In the presence of 100 μM glutamate, RGC number decreased to 55 ± 4% of control (mean ± SEM, n = 76; P < 0.001). The glutamate effect was completely eliminated by MK801, an NMDA receptor antagonist. Trophic factor withdrawal also caused a similar loss of RGCs (54 ± 4%, n = 60, P < 0.001). PEDF protected against both insults with EC(50 )values of 13.6 ng/mL (glutamate) and 3.4 ng/mL (trophic factor withdrawal), respectively. At 100 ng/mL, PEDF completely protected the cells from both insults. Inhibitors of the nuclear factor κB (NFκB) and extracellular signal-regulated kinases 1/2 (ERK1/2) significantly reduced the protective effects of PEDF. CONCLUSION: We demonstrated that PEDF potently and efficaciously protected adult rat RGCs from glutamate- and trophic factor withdrawal-mediated cytotoxicity, via the activation of the NFκB and ERK1/2 pathways. The neuroprotective effect of PEDF represents a novel approach for potential treatment of retinopathies, such as glaucoma

Alleviation of cisplatin-induced acute kidney injury using phytochemical polyphenols is accompanied by reduced accumulation of indoxyl sulfate in rats

Background:Polyphenols such as quercetin have been reported to prevent cisplatin-induced acute kidney injury (AKI). Indoxyl sulfate (IS), a uremic toxin generated in the liver, is increased in cisplatin AKI. The present study examined the effect of phytochemical polyphenols on serum and renal accumulations of IS in association with cisplatin AKI. Methods:Sprague-Dawley rats were treated with cisplatin (10 mg/kg body weight) by intraperitoneal injection. Polyphenols were orally administered at -24, -1, 24 and 48 hr before or after cisplatin injection. Serum levels of IS, cisplatin, serum creatinine (SCr), blood urea nitrogen (BUN) and electrolytes were measured. By using in vitro assay system with rat liver S9 fraction, the inhibitory potencies of several compounds on IS production were determined. Results:Injection of cisplatin in rats markedly elevated the SCr and BUN levles, which were accompanied by tubular injuries and the expression of kidney injury molecule-1 (Kim-1). By contrast, quercetin significantly suppressed the SCr and BUN levels in the cisplatin-treated rats and protected them against renal injury with the decreased expression of Kim-1. Quercetin had no effect on serum and renal levels of cisplatin. In addition, quercetin had no effect on cisplatin-induced renal accumulation of malondialdehyde. IS concentrations in serum, kidney, liver, intestine and lung were markedly elevated by cisplatin treatment, whereas quercetin suppressed the serum and tissue IS levels. An in vitro kinetic assay revealed that quercetin displayed a potent inhibitory effect on hepatic production of IS.Conclusion:Inhibition of IS accumulation by oral administration of quercetin alleviates cisplatin-induced AKI