Anti-inflammatory Function of Phyllostachys Edulis Extract in the Hippocampus of HIV-1 Transgenic Rats

Abstract

HIV induces neuroinflammation. We evaluated the anti-inflammatory effect of an extract from bamboo Phyllostachys edulis in the hippocampus of HIV-1 transgenic (TG) rats. Five (5) one-month-old TG rats and 5 Fisher 344 (F344) rats were fed a control diet, another 5 TG rats were fed the control diet supplemented with bamboo extract (BEX, 11 grams dry mass per 4057 Kcal). After 9 months of dietary treatment, the gene and protein expression of interleukin 1 beta (IL-1β), glial fibrillary acidic protein (GFAP), and ionized calcium-binding adapter molecule 1 (Iba1), and the protein expression p65 and c-Jun were analyzed in the hippocampus. Compared to the F344 rats, the TG rats fed control diet showed significantly higher protein expression of GFAP and c-Jun, and mRNA and protein levels of IL-1β. BEX supplement to the TG rats significantly lowered protein expressions of GFAP, p65, and c-Jun, and showed a trend to decrease the protein expression of IL-1β. Compared to the TG rats, TG+BEX rats also downregulated the mRNA levels of IL-1β and TNFα. In summary, neuroinflammation mediated by the NFκB and AP-1 pathways in the hippocampus of the TG rats was effectively abolished by dietary supplement of BEX.

Keywords: AP-1; HIV; NFκB; bamboo Phyllostachys edulis extract; hippocampus; neuroinflammation.

Figure 1

Energy consumption, body and brain weight of F344 rats fed control diet (F344), HIV-1 transgenic rats fed control diet (TG), and HIV-1 transgenic rats supplemented with BEX (TG+BEX). A, Energy consumption over 9 months. B, Body weight before decapitation. C, Wet brain weight. D, Percentage of brain weight over body weight. Average and SD are shown, n=5 per group. The P value labeled in panel B was from one-way ANOVA. *, p<0.05, Bonferroni’s multiple comparison,

Figure 2

Protein and gene expression of glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (Iba1) in the hippocampus of F344 rats fed control diet (F344), HIV-1 transgenic rats fed control diet (TG), and HIV-1 TG rats supplemented with BEX (TG+BEX). A, Western blot image of GFAP, Iba1, and loading control β-actin. B, Relative quantification of GFAP protein expression. C, Relative quantification of Iba1 protein expression. D, Correlation between the protein levels of GFAP and Iba1. E, Relative mRNA expression of GFAP. F, Relative mRNA expression of Iba1. Average and SD are shown, n=5 per group. P values labeled in panels B and C were from Kruskal-Wallis test; and that in panel D was from linear regression. # p<0.05, Dunn’s multiple comparison test; * p<0.05, Mann Whitney test. For western blot, all samples were run on the same gel.

Figure 3

Protein and gene expression of interleukin-1β (IL-1β) and tumor necrosis factor α (TNFα) in the hippocampus of F344 rat fed control diet (F344), HIV-1 transgenic rats fed control diet (TG), and HIV-1 transgenic rats supplemented with BEX (TG+BEX). A, Western blot image of IL-1β and loading control β-actin. B, Relative quantification of IL-1β protein expression. C, Relative quantification of IL-1β mRNA expression. D, Relative quantification of TNFα mRNA expression. Average and SD are shown, n=5 per group. P values in panels B and C were from Kruskal-Wallis test. # p<0.05, Dunn’s multiple comparison test; * p<0.05, Mann Whitney test; ^ p=0.056, Mann Whitney test. For western blot, all samples were run on the same gel.

Figure 4

Protein expression of p65 and c-Jun in the hippocampus of F344 rat fed control diet (F344), HIV-1 transgenic rats fed control diet (TG), and HIV-1 transgenic rats supplemented with BEX (TG+BEX). A, Western blot image of p65, c-Jun and loading control β-actin. B, Relative quantification of p65 protein expression. C, Relative quantification of c-Jun protein expression. Average and SD are shown, n=5 per group. P values in panels B and C were from Kruskal-Wallis test. # p<0.05, Dunn’s multiple comparison test; * p<0.05, Mann Whitney test. For western blot, all samples were run on the same gel.