Plantago asiatica L. Ameliorates Puromycin Aminonucleoside-Induced Nephrotic Syndrome by Suppressing Inflammation and Apoptosis

Abstract

Objective: Nephrotic syndrome, a kidney disease with a variety of causes, is mainly characterized by heavy proteinuria, hypoproteinemia, and ascites. This study was designed to evaluate the underlying mechanism of action of Plantago asiatica L. (PAL) in treating nephrotic syndrome induced by puromycin aminonucleoside.

Methods: PAL has been used in Asia as a traditional medicine and dietary health supplement. Sprague-Dawley (SD) rats were intravenously injected with puromycin aminonucleoside (75 mg/kg/day), then treated with either Losartan (30 mg/kg/day) or PAL (200 mg/kg/day) by oral gavage for seven days.

Results: PAL significantly decreased ascites, proteinuria level, and plasma lipid parameters. In addition, treatment with PAL attenuated histological damage and hypoalbuminemia. Treatment with PAL also restored podocin expression and reduced inflammation markers such as intracellular adhesion molecules (ICAM-1), monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor alpha (TNF-α) and high-mobility group box-1 (HMGB1). Lower expression levels of the apoptosis markers Bax, caspase-3 and capase-9 were documented in SD rats receiving PAL. PAL also significantly decreased the phosphorylation levels of MAPKs such as ERK, JNK and p38.

Conclusion: As a multifunctional agent, PAL has a renoprotective effect in nephrotic syndrome rat models. The anti-inflammatory and anti-apoptotic properties, along with reductions in hyperlipidemia and ascites, represent important therapeutic effects. These results indicate that Plantago asiatica is likely to be a promising agent in the treatment of nephrotic syndrome.

Keywords: apoptosis; ascites; inflammation; nephrotic syndrome; plantago asiatica.

Figure 1

Effects of Plantago asiatica L. (PAL) on urinary protein excretion at various time points (A) and ascites (B). Values were expressed as mean ± SE (n = 7). ** p < 0.01 versus Control; ^# p < 0.05, ^## p < 0.01 versus NS.

Figure 2

Effects of treatment of PAL on renal morphology. Representative photomicrographs of PAS (Periodic acid-chiff)-stained tissues (magnification ×200). The bottom panels represent quantitative assessments of protein cast area. Protein casts in the distal tubules are indicated by black arrows in the pictures. Values were expressed as mean ± SE (n = 7). * p < 0.05 versus Control.; ^# p < 0.05 versus NS.

Figure 3

Effects of treatment of PAL on renal podocin expression. The top panels show immunohistochemistry staining (magnification ×400) (A) and western blot (B) of renal cortical tissue. The bottom panels represent quantitative assessments of podocin expression. Values were expressed as mean ± SE (n = 7). ** p < 0.01 versus Control.; ^# p < 0.05, ^## p < 0.01 versus NS.

Figure 4

Effect of PAL on the expression of inflammation markers in renal tissues. The whole kidney extracts were prepared, and ICAM-1, MCP-1, HMGB-1 and TNF-α were analyzed by western blot analysis. Each electrophoretogram represents the results from three individual experiments. ** p < 0.01 versus Control.; ^## p < 0.01 versus NS.

Figure 5

Effect of PAL on the expression of apoptosis-related markers in renal tissues. Whole-kidney extracts were assayed for Bcl-2, Bax, Caspase-2 and Caspase-9 by western blot analysis. Each electrophoretogram is representative of the results from three individual experiments. * p < 0.05, ** p < 0.01 versus Control.; ^## p < 0.01 versus NS.

Figure 6

Effect of PAL on the expression of MAPK in renal tissues. MAPKs were detected by specific antibodies and compared to the corresponding signals from phosphorylated MAPKs. Whole-kidney extracts were assayed for phosphorylated MAPKs western blot analysis. Each electrophoretogram is representative of the results from three individual experiments. ** p < 0.01 versus Control.; ^## p < 0.01 versus NS.