Ellagic acid restored lead-induced nephrotoxicity by anti-inflammatory, anti-apoptotic and free radical scavenging activities

Abstract

Introduction: long-term environmental and occupational exposure to lead, which is a ubiquitous industrial pollutant, causes significant damage to tissues of kidney. This report aims to address this debilitating issue. A natural polyphenolic compound, Ellagic acid (EA) is having numerous potential medicinal properties. In this present study nephroprotective effects of EA has been evaluated in a rodent model with lead-induced toxicity.

Methods: Rats were treated with EA doses of 50 mg/kg and 25 mg/kg and simultaneously co-administered with lead acetate (60 mg/kg) for 2 months through oral route. The extent to which EA treatment provides nephroprotective effect was estimated by measurement of serum biomarkers, tissue antioxidants, inflammatory mediators, apoptosis, autophagy pathway and histological examination.

Results: EA treatment caused significant restoration in the level of serum biomarkers, tissue antioxidants and histological architecture of renal tissue. Treatment with either of the doses of EA causes restoration of pro-inflammatory mediators to approximately pre-exposure concentration. This phenomena is caused by suppression of expression levels of inflammatory molecules like tumour necrosis factor-α (TNF-α), nuclear factor kappa B (NF-κB), interleukin-6 (IL-6), and interleukin-1β (IL-1β), as well as functional expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, it was also observed that EA suppressed apoptotic and autophagic pathway by reduction of expression of light chain 3B (LC3B) level which are the oxidative DNA damage markers of renal tissue.

Conclusion: It can be safely concluded that EA provides protection against lead-induced nephrotoxicity to a significant degree.

Keywords: Apoptosis; Autophagy; Ellagic acid; Inflammation; Lead; Nephrotoxicity.

Figure 1

Effect of Ellagic acid treatment on kidney NF-κβ, IL-6 and IL-1β against lead acetate induced Nephrotoxicity. All values are mean ± SEM, n = 8, ∗∗∗P < 0.001 when compared to Negative control; ^###P < 0.001 compared to Positive control group. EA 50: Ellagic acid (50 mg/kg) EA 25: Ellagic acid (25 mg/kg). NC: Negative Control, PC: Positive Control.

Figure 2

Effect of Ellagic acid treatment on kidney TNF α against lead acetate induced Nephrotoxicity. All values are mean ± SEM, n = 8, ∗∗∗P < 0.001 when compared to Negative control; ^###P < 0.001 compared to Positive control group. EA 50: Ellagic acid (50 mg/kg) EA 25: Ellagic acid (25 mg/kg). NC: Negative Control, PC: Positive Control.

Figure 3

Effect of Ellagic acid treatment on kidney COX-2 against lead acetate induced Nephrotoxicity. All values are mean ± SEM, n = 8, ∗∗∗P < 0.001 when compared to Negative control; ^###P < 0.001 compared to Positive control group. EA 50: Ellagic acid (50 mg/kg) EA 25: Ellagic acid (25 mg/kg). NC: Negative Control, PC: Positive Control.

Figure 4

Effect of Ellagic acid treatment on kidney iNOS against lead acetate induced Nephrotoxicity. All values are mean ± SEM, n = 8, ∗∗∗P < 0.001 when compared to Negative control; ^###P < 0.001 compared to Positive control group. EA 50: Ellagic acid (50 mg/kg) EA 25: Ellagic acid (25 mg/kg). NC: Negative Control, PC: Positive Control.

Figure 5

Effect of Ellagic acid treatment on kidney LC3B against lead acetate induced Nephrotoxicity. All values are mean ± SEM, n = 8, ∗∗∗P < 0.001 when compared to Negative control; ^###P < 0.001 compared to Positive control group. EA 50: Ellagic acid (50 mg/kg) EA 25: Ellagic acid (25 mg/kg). NC: Negative Control, PC: Positive Control.

Figure 6

Haematoxylin and eosin (H&E) stained section of kidney in lead acetate induced kidney damage. Necrosis (red arrow), inflammatory infiltration (black arrow) and increased thickness of basement membrane (yellow arrow) Photographed at magnification 100X; a: (H&E) stained microscopic kidney section (100X) of Negative control rats, Scale bar, (150 μm); b: (H&E) stained kidney section (100X) of Positive control rats showing areas of severe necrosis of proximal tubules, Scale bar, (150 μm); c: (H&E) stained kidney section (100X) of EA25 treated rats showing mild congestion. Scale bar, (150 μm); d: (H&E) stained kidney section (100X) of EA50 treated rats showing mild degree of peritubular and glomerular congestion. Scale bar, (150 μm).