Table 2 Major clinical and clinically relevant studies have revealed gut‒brain or gut‒immune‒brain axes in neurological disorders
From: Beyond the gut: decoding the gut–immune–brain axis in health and disease
Disorder | Model | Axis | Key findings | Ref. |
|---|---|---|---|---|
ASD | Humanized GF and BTBR Mouse Models | Gut Microbiota-Brain | Human ASD patient microbiota can induce ASD phenotypes in GF mice ↑ Bacteriodetes, β-Proteobacteria, Lactobacillales, Clostridiacseae, and Enterobacteriaceae in ASD-FMT murine offspring 5-aminovaleric acid and taurine improves ASD | [381] |
Clinical | Gut Microbiota-Brain | ↑ Clostridium, Streptococcus, Acinetobacter, and Alcaligenaceae in ASD ↑ Arginase metabolism in ASD | [305] | |
Clinical | Gut Microbiota-Brain | ↓ Butyrate producing microbes in ASD | [306] | |
Clinical | Gut Microbiota-Brain | ↓ Bacteroidetes ↑ Catenibacterium, Tenericutes in ASD | [307] | |
Clinical | Gut Microbiota-Brain | ↑Lactobacillaceae, Bacteroides, Parabacteroides, Proteus ↓ Bifidobacterium, Prevotella, Bacteroidetes, Blautia in ASD ↑ Zinc, Copper, Nickel in ASD | [308] | |
Clinical | Gut Microbiota-Metabolite-Brain | ↓Prevotella, Megamonas ↑ Escherichia-Shigella, Dialister, Bifidobacterium Disrupted lipid, vitamin, glycan, xenobiotic, and amino acid metabolisms | [325] | |
Clinical | Metabolite-Brain | ↑ Glutamate, citrulline, acetylcarnitine, lactate, choline, ornithine, glycine, histidine, free fatty acids in ASD | ||
Clinical | Metabolite-Brain | ↑ GABA degradation into butyrate | [314] | |
Clinical | Metabolite-Brain | ↑ lactate, alanine, glycerol-3-phosphate, threonine, linoleic acid, linoleylcarnitine, cholesterol, ceramides ↓ anti-inflammatory and antioxidant molecules (glutathione, carnosine, carnitine, betaine, 5’methyltetrahydrofolic acid, CoQ10), bile acid metabolism, dopamine, serotonin in ASD | [315] | |
Clinical | Immune-Brain | ↑ IL-1β, IL-6, IL-8, IL-12, IL-17, IFN-γ, and TNF-α in blood among ASD | ||
Clinical | Immune-Brain | ↑ IL-1β, IL-6, IL-17, and TNF-α in brain among ASD | [319] | |
AD | Clinical | Gut Microbiota-Brain | ↓ Microbiota richness, Firmicutes, SMB53, Dialister, Clostridium, Turicibacter, Bifidobacterium, Adlercreutzia ↑ Bacteroidetes, Blautia, Phascolarctobacterium, Gemella, Bacteroides, Alistipes | [327] |
Clinical | Gut Microbiota-Brain | ↑ Dorea formicigenerans, Oscilibacter sp. 57_20, Faecalibacterium prausnitzii, Coprococcus catus, Anaerostipes hadras in preclinical AD ↑ Bacteroides caccae, Bifidobacterium longum, Bacteroides faecis, Bacteroides salyersiae, Bacteroides massiliensis in healthy | [382] | |
Clinical | Gut Microbiota-Brain | ↑ Correlation between higher cognitive performance with Bacteroides massiliensis, Bifidobacterium pseudocatenulatum, Fusicatenibacter saccharivorans, Eggerthella lenta | [330] | |
Clinical | Gut Microbiota-Immune-Brain | ↓ Butyrate-producing bacteria ↑ proinflammatory-associated bacteria in AD | [329] | |
Depression | Clinical | Gut Microbiota-Immune-Brain | ↑ Paramecium excretum, Parasutterella, lysine biosynthesis and methionine biosynthesis pathways in depression Correlation with CD8, CD11b, and CD27 B cells in depression | [335] |
Clinical and Humanized Mouse Model | Gut Microbiota-Immune-Brain | ↑ Bacteroides, TNF, MCSF, IL-12 ↓ Clostridiumn, Roseburia, Haemophilus, SMB53, and Turicibacter FMT of depression microbiota can induce inflammatory depression via TLR4/NF-κB SCFA can regulate inflammation and symptoms | [336] | |
Clinical and Chronic Social-defeat Stress Mouse Model | Gut Microbiota-Immune-Brain | ↑ Lactobacillus correlated with lower depression rating scales in depression patients ↑ γδ17 T cells in colon and meninges in depressed mice | [337] |
