Enterococcus faecalis SI-FC-01 enhances the stress resistance and healthspan of C. elegans via AKT signaling pathway

Abstract

The global demographic is witnessing an unprecedented surge in aging, precipitating a dramatic rise in geriatric diseases and related health complications. Although probiotics have been extensively shown to maintain microbiome stability and confer health benefits, their potential role in decelerating the aging process remains largely unexplored. The study identified a beneficial gut microbe from human intestinal tract, Enterococcus faecalis SI-FC-01, which was proved to be biosafe and found to enhance the average lifespan of C. elegans by 33.55%. More interestingly, the E. faecalis SI-FC-01 also enhanced the motor ability, memory and learning ability and anti-oxidative stress ability of C. elegans. Moreover, it exhibited neuroprotective effects in the worm models of neurodegenerative diseases such as Parkinson's disease and Huntington's disease. Through screening various aging-associated mutants of C. elegans, we discovered that E. faecalis SI-FC-01 modulates DAF-16/FOXO signaling via the activation of AKT pathway. This activation subsequently triggers stress resistance and immune-related genes downstream of daf-16, thereby promoting healthspan and neuroprotection. In summary, our research indicates that E. faecalis SI-FC-01 holds significant potential as a dietary supplement for delaying host aging. Furthermore, it provides novel insights for potentially mitigating the progression of age-related neurodegenerative diseases.

Keywords: Caenorhabditis elegans; Enterococcus faecalis; Aging; Healthspan; Neurodegenerative diseases.

Fig. 1

E. faecalis SI-FC-01 prolonged the lifespan of C. elegans. The effect of Enterococcus faecalis SI-FC-01 and 50mM metformin on worm lifespan regulation was determined, and control worms were fed with E. coli OP50. (N = 90 worms, p < 0.001, Log rank test).

Fig. 2

E. faecalis SI-FC-01 can improve the health of C. elegans. (a) The body size from wild-type (N2) worms grown on E. coli OP50 and E. faecalis SI-FC-01 (N = 30 worms, p > 0.05, F-test). (b) Effect of feeding E. coli OP50 or E. faecalis SI-FC-01 on gonadal cell apoptosis in N2 worms (N = 90 worms, Student’s t-test). (c) The head thrashes from 4D, 8D and 12D wild-type (N2) worms grown on E. coli OP50 and E. faecalis SI-FC-01 are significantly different at p < 0.05, p < 0.05 and p < 0.001 (N = 60, Student’s t-test). (d) Altered salinity tropism after salt aversion learning in wild-type worms N2 fed E. coli OP50 or E. faecalis SI-FC-01 (N ≥ 300 worms, p < 0.001 and p < 0.001, two-way ANOVA). e Changes in accumulation of lipofuscin in wild-type worms N2 after E. faecalis SI-FC-01 feeding in 4D,8D,12D. (N = 60 worms per time period, Student’s t test)

Fig. 3

The transcriptome of C. elegans fed with E. coli OP50 or E. faecalis SI-FC-01. Differential gene expression analysis, the red and blue dots in the figure indicate significantly up- and down-regulated genes with |log FC| ≥ 1 and p < 0.05, and black points are non-significantly different genes (a, b). (a) scatter plot. The x- and y-axes are the expression of the gene in the E. coli OP50 group and in the E. faecalis SI-FC-01 group. (b) Volcano plot. The x-axis is the value of the fold change log2(FC) in gene expression differences between E. faecalis SI-FC-01 treated worms and E. coli OP50 treated worms, and the y-axis is the negative logarithm of the p-value. (c) GO Enrichment pathway analysis with significant changes between E. coli OP50 and E. faecalis SI-FC-01 group. (d) GO enrichment analysis of genes with significant changes between E. coli OP50 and E. faecalis SI-FC-01 group.

Fig. 4

E. faecalis SI-FC-01 acts on the AKT signaling pathway to delay aging. (a) Relative expression of daf-16 upstream genes in 8-day-old worms (N2) treated with E. faecalis SI-FC-01 (Student’s t-test). (b) The altered fluorescence signal of the TJ356 daf-16(zls356) fed with E. faecalis SI-FC-01 (N = 90 worms, p < 0.001, Student’s t-test). (c) Relative expression of AKT pathway-related genes in 8-day-old worms (N2) treated with E. faecalis SI-FC-01 (Student’s t-test). Survival curves of AKT signaling pathway mutants, CF1038 daf-16(mu86) (d), TJ1052 age-1(hx546) (e), GR1310 akt-1(MG144) (f), VC204 akt-2(ok393) (g) (N = 90 worms, p > 0.05, Log rank test).

Fig. 5

E. faecalis SI-FC-01 can enhance the stress resistance of C. elegans via AKT signaling pathway. a The changes in lifespan of wild type worms N2 treated with E. faecalis SI-FC-01 after heat stress at 35°C (N = 90 worms, two-way ANOVA). The changes in lifespan of N2 (b), TJ1052 age-1(hx546) (c), GR1310 akt-1(MG144) (d), VC204 akt-2(ok393) (e), CF1038 daf-16(mu86) (f) treated with E. faecalis SI-FC-01 after H₂O₂ oxidative stress (N = 90 worms, two-way ANOVA). (g) Relative expression of daf-16 downstream genes in 8-day-old worms (N2) treated with E. faecalis SI-FC-01 (Student’s t-test).

Fig. 6

E. faecalis SI-FC-01 can delay the progression of age-related diseases in models of degenerative disease C. elegans. (a) Effect of E. faecalis SI-FC-01 treatment on Poly-Q accumulation on 4D and 8D PD model worm AM140 (N = 90 worms, p < 0.01 and p < 0.01, Student’s t-test). (b) Repair of dopamine neurons in 6-OH DA treated BZ555 strain by E. faecalis SI-FC-01 treatment (N = 90 worms, p < 0.05, Student’s t-test).