Cross-Regulation between Autophagy and Apoptosis Induced by Vitamin E and Lactobacillus Plantarum through Beclin-1 Network

Abstract

Autophagy and apoptosis are two important regulatory mechanisms for how the body can respond to diseases. This study was designed to investigate the protective actions of vitamin E (Vit-E) and lactobacillus plantarum (Lac-B) against mercuric chloride (HgCl₂)-induced kidney injury. Thirty albino rats were divided into five groups: group 1 served as the normal group; rats in group 2 received high doses of HgCl₂; rats in groups 3, 4 and 5 were given Vit-E, Lac-B and the combination of Vit-E and Lac-B, respectively along with HgCl₂ for two weeks. HgCl₂ provoked renal injury, manifested by elevation in serum urea, urea nitrogen and creatinine. Kidney levels of oxidative stress and inflammation were markedly increased post HgCl₂ administration. Moreover, HgCl₂ significantly elevated the gene expression levels of VCAM-1 and cystatin C, while podocin was downregulated. Additionally, it markedly decreased the protein expression of Beclin-1 and Bcl-2. Histopathological examination revealed massive degeneration with congested blood vessels following HgCl₂ administration. Treatment with Vit-E or/and Lac-B restored the normal levels of the previously mentioned parameters, as well as improved the morphology of kidney tissues. Both Vit-E and Lac-B provided a protective effect against HgCl₂-induced kidney damage by regulating autophagy and apoptosis.

Keywords: Beclin-1; Lactobacillus-plantarum; apoptosis; autophagy; vitamin E.

Figure 1

Vit-E and Lac-B prevented HgCl₂-induced renal injury in rats. Treatments with Vit-E and Lac-B either alone or in combination ameliorated serum urea, urea nitrogen and creatinine levels. Data are expressed as mean ± SEM, (n = 6). ** p < 0.01 and *** p < 0.001.

Figure 2

Vit-E and Lac-B attenuated HgCl₂-induced renal injury in rats. Treatments with Vit-E and Lac-B either alone or in combination decreased renal MDA and increased GSH and SOD. Data are expressed as mean ± SEM, (n = 6). ** p < 0.01 and *** p < 0.001.

Figure 3

Vit-E and Lac-B upregulated renal Beclin-1 and Bcl-2 expression in HgCl₂-intoxicated rats. Representative blots show changes in the expression of Bcl-2 and Beclin-1 in all treated groups. Data were expressed as mean ± SEM, (n = 6). ** p < 0.01 and *** p < 0.001.

Figure 4

Vit-E and Lac-B suppressed renal cystatin C, VCAM-1 and increased podocin mRNA expression in HgCl₂-intoxicated rats. Representative blots are showing variations in the expression of cystatin C, podocin, VCAM-1 and β-actin in all treated groups. Data were expressed as mean ± SEM, (n = 6). ** p < 0.01 and *** p < 0.001.

Figure 5

Vit-E and Lac-B attenuated HgCl₂-induced renal inflammation in rats. Treatment with Vit-E and Lac-B either alone or in combination decreased renal inflammatory biomarkers (IL-6 and TNF-α). Data are expressed as mean ± SEM, (n = 6). *** p < 0.001.

Figure 6

Vit-E and Lac-B suppressed renal apoptotic damage in HgCl₂-intoxicated rats. (A) Representative blot is showing variations in the DNA fragmentation in all treated groups, (B) changes in renal tissue expression of Caspase 3 in all treatment groups. Data are expressed as mean ± SEM, (n = 6). *** p < 0.001, * p < 0.05.

Figure 7

Photomicrograph of H&E-stained sections of rat kidney. (A) section from normal control rat shows normal histological appearance of renal corpuscle with normal glomerulus (black arrow). (B) section of kidney from rat received HgCl₂ showed few of the glomeruli corpuscles are obliterated and destructed (hyperplasia of epithelial cells lining the partial layer of Bowman’s capsule) (black arrow). Proximal convoluted tubules show destructed epithelial lining (yellow arrow), destructed epithelial lining of distal convoluted tubules (red arrow), (C) section of kidney from HgCl₂ administrated rat treated by Vit-E showed few of the glomeruli corpuscles are obliterated and destructed (hyperplasia of epithelial cells lining the partial layer of Bowman’s capsule) (black arrow). Proximal convoluted tubules show the destructed epithelial lining (yellow arrow), destructed epithelial lining of distal convoluted tubules (red arrow). (D) section from HgCl₂ administrated rat received Lac showed renal cortex showing renal corpuscle with almost normal glomerulus (red arrow), mildly dilated proximal convoluted (black arrow) and mildly dilated distal convoluted (yellow arrow) tubules. (E) section of kidney from HgCl₂ administrated rat treated by (Vit-E+ Lac) showed renal cortex showing renal corpuscle with normal glomerulus (red arrow), normal pattern of proximal convoluted (black arrow) and distal convoluted (yellow arrow) tubules (Scale bar; 400 µm).