A novel Mediterranean diet-inspired supplement ameliorates cognitive, microbial, and metabolic deficits in a mouse model of low-grade inflammation

Abstract

The Mediterranean diet (MD) and its bioactive constituents have been advocated for their neuroprotective properties along with their capacity to affect gut microbiota speciation and metabolism. Mediated through the gut brain axis, this modulation of the microbiota may partly contribute to the neuroprotective properties of the MD. To explore this potential interaction, we evaluated the neuroprotective properties of a novel bioactive blend (Neurosyn240) resembling the Mediterranean diet in a rodent model of chronic low-grade inflammation. Behavioral tests of cognition, brain proteomic analysis, 16S rRNA sequencing, and ¹H NMR metabolomic analyses were employed to develop an understanding of the gut-brain axis interactions involved. Recognition memory, as assessed by the novel object recognition task (NOR), decreased in response to LPS insult and was restored with Neurosyn240 supplementation. Although the open field task performance did not reach significance, it correlated with NOR performance indicating an element of anxiety related to this cognitive change. Behavioral changes associated with Neurosyn240 were accompanied by a shift in the microbiota composition which included the restoration of the Firmicutes: Bacteroidota ratio and an increase in Muribaculum, Rikenellaceae Alloprevotella, and most notably Akkermansia which significantly correlated with NOR performance. Akkermansia also correlated with the metabolites 5-aminovalerate, threonine, valine, uridine monophosphate, and adenosine monophosphate, which in turn significantly correlated with NOR performance. The proteomic profile within the brain was dramatically influenced by both interventions, with KEGG analysis highlighting oxidative phosphorylation and neurodegenerative disease-related pathways to be modulated. Intriguingly, a subset of these proteomic changes simultaneously correlated with Akkermansia abundance and predominantly related to oxidative phosphorylation, perhaps alluding to a protective gut-brain axis interaction. Collectively, our results suggest that the bioactive blend Neurosyn240 conferred cognitive and microbiota resilience in response to the deleterious effects of low-grade inflammation.

Keywords: Akkermansia; Gut-brain axis; cognition; inflammation; microbiota; neurodegenerative disease.

Graphical abstract

Figure 1.

Body weight in response to LPS and Neurosyn240 treatments. a) There was no significant weight difference across groups throughout the 8-week experimentation, b) Total body weight gain did not significantly differ across groups. Data are represented as the mean ± standard error of the mean (s.e.m.). n = 10 mice per group. ns, not significant. LPS: Lipopolysaccharide.

Figure 2.

Neurosyn240 improves LPS mediated reduction in cognitive performance a) nor performance significantly dropped in response to LPS treatment but was subsequently restored through Neurosyn240 supplementation. b) Although not significant, of time in center appeared to drop in response to LPS and was partially recovered by Neurosyn240 supplementation. c) Similar to OF, Y maze performance although not significant appeared to be reduced by LPS treatment with slight recovery observed through Neurosyn240 supplementation. Data are represented as the mean ± standard error of the mean (s.e.m.). n = 10 mice per group. *p < p < 0.05, **p < 0.01. ns: not significant. OF: Open field; NOR: Novel object recognition; LPS: Lipopolysaccharide.

Figure 3.

Neurosyn240 alters gut microbial profile which may influence nor performance a) Relative abundance of microbiota at the phylum (left) and class (right) levels in the indicated groups. b) Alpha diversity as analyzed using chao1 was significantly increased through Neurosyn240 treatment, c) but no significant difference was established using Shannon diversity index. d) PCA of beta diversity measured through Bray-Curtis analysis was significantly different across experimental groups. e) the Firmicutes to Bacteroidota ratio was significantly altered in response to LPS insult but was subsequently restored through Neurosyn240 treatment. f) at the genus level the Neurosyn240 intervention resulted in an increased in Akkermansia g) the abundance of Akkermansia correlated with nor performance. Data are represented as the mean ± standard error of the mean (s.e.m.). (n = 6 per group). *p < 0.05, **p < 0.01 ns: not significant.

Figure 4.

The gut metabolomic profile is altered by LPS and premix treatment a) PLS-DA plot showed separation of groups indicative of a metabolomic shift in response to treatment. (n ≥ 5); b) Volcano plot depicting the 19 significantly altered metabolites (FDR q < 0.05). c) Correlation analysis between metabolomics data and microbiome data conducted using M2IA. *p < 0.05, **p < 0.01.

Figure 5.

Brain proteomic profile is altered by LPS and Neurosyn240 treatment a) Protein–protein interaction analysis using STRING highlight Alzheimer’s disease, Oxidative phosphorylation, metabolic pathways and retrograde endocannabinoid signaling as highly altered pathways; b) Subsequent heatmap depicting the highlighted proteins associate with these pathways; c) Cluster of proteins that are reduced by LPS and recovered by Neurosyn240 are highly related to oxidative phosphorylation.

Figure 6.

Brain proteomic profile partially correlates with Akkermansia abundance. a) Protein–protein interaction analysis using STRING highlight Alzheimer’s disease and oxidative phosphorylation as being the most activated. b) Abundance of these key proteins.