Orally administered Odoribacter laneus improves glucose control and inflammatory profile in obese mice by depleting circulating succinate

Abstract

Background: Succinate is produced by both human cells and by gut bacteria and couples metabolism to inflammation as an extracellular signaling transducer. Circulating succinate is elevated in patients with obesity and type 2 diabetes and is linked to numerous complications, yet no studies have specifically addressed the contribution of gut microbiota to systemic succinate or explored the consequences of reducing intestinal succinate levels in this setting.

Results: Using germ-free and microbiota-depleted mouse models, we show that the gut microbiota is a significant source of circulating succinate, which is elevated in obesity. We also show in vivo that therapeutic treatments with selected bacteria diminish the levels of circulating succinate in obese mice. Specifically, we demonstrate that Odoribacter laneus is a promising probiotic based on its ability to deplete succinate and improve glucose tolerance and the inflammatory profile in two independent models of obesity (db/db mice and diet-induced obese mice). Mechanistically, this is partly mediated by the succinate receptor 1. Supporting these preclinical findings, we demonstrate an inverse correlation between plasma and fecal levels of succinate in a cohort of patients with severe obesity. We also show that plasma succinate, which is associated with several components of metabolic syndrome including waist circumference, triglycerides, and uric acid, among others, is a primary determinant of insulin sensitivity evaluated by the euglycemic-hyperinsulinemic clamp.

Conclusions: Overall, our work uncovers O. laneus as a promising next-generation probiotic to deplete succinate and improve glucose tolerance and obesity-related inflammation. Video Abstract.

Keywords: Animal models; Glucose tolerance; Inflammation; Obesity; Probiotics; Succinate.

Fig. 1

Gut microbiota and dietary regimen regulate intestinal and circulating succinate levels. Succinate levels in the cecum (a), colon (b), and serum (c) of conventional C57BL/6 (CVN) and germ-free (GF) mice (n = 16–19: males = 9–10; females = 7–9). Circulating succinate determination after intra-colon administration of 500 mg/kg of disodium succinate (or saline as vehicle) in C57BL/6 wild-type mice fed with chow diet (CD) (n = 4) (d). Succinate levels in the cecum (e), feces (f), and serum (g) of C57BL/6 mice fed high-fat diet (HFD) or CD (n = 10). Data are expressed as mean + s.e.m (a–d,f) or % over control (e). *p < 0.05; **p < 0.01; ***p < 0.001 (unpaired t-test and two-way ANOVA)

Fig. 2

Microbiota depletion improves glucose metabolism and reduces succinate levels in C57BL/6 diet-induced obese mice. Percentage of 16S rRNA gene detection in cecum before and after antibiotic or vehicle administration (a). Cecal short-chain fatty acid analysis: acetic acid (AA), propionic acid (PA), butyric acid (BA), indolebutyric acid (IBA), isovaleric acid (IVA), valeric acid (VA), and hexanoic acid (HA) (b) (n = 6–8). Body weight evolution (c). Food consumption (d). Glucose (e) and insulin (f) tolerance tests (n = 8–10). mRNA expression levels of inflammatory genes in the scWAT, vWAT, liver, and intestine (g) (n = 6). Succinate levels in the cecum (h), feces (i), and serum (j) (n = 6–8). Data are presented as mean + s.e.m. *p < 0.05; **p < 0.01; ***p < 0.001 (unpaired t-test and two-way ANOVA)

Fig. 3

Probiotic intervention with Odoribacter laneus depletes serum succinate and moderates inflammation in db/db mice. Effect of different probiotic interventions on body weight (a), food intake (b), and fasted serum succinate levels (c) (n = 8–10). Principal component analysis and average phylum, family, genera, and species abundance of the 10 more abundant taxa in the cecum of db/db mice treated with vehicle or O. laneus (d) (n = 15). mRNA expression levels of inflammatory genes in the scWAT, vWAT, liver, and intestine (e) (n = 7–10). Data are presented as mean + s.e.m. *p < 0.05; **p < 0.01; ***p < 0.001 (unpaired t-test)

Fig. 4

Probiotic intervention with Odoribacter laneus ameliorates glucose tolerance and inflammation in mice with diet-induced obesity. Weight evolution (a) and food consumption (b) during probiotic treatment (n = 7). Fasted serum succinate levels (n = 5–6) (c). Principal component analysis and average phylum, family, genera, and species abundance of the 10 more abundant taxa in the cecum of DIO mice treated with vehicle or O. laneus (d) (n = 6–8). Glucose tolerance test (e) (n = 7). Insulin secretion during glucose tolerance test (f) (n = 5). Insulin tolerance test (g) (n = 7). mRNA expression levels of inflammatory genes in the scWAT, vWAT, liver, and intestine (h) (n = 5). Data are presented as mean + s.e.m. *p < 0.05; **p < 0.01 (unpaired t-test and two-way ANOVA)

Fig. 5

Probiotic intervention with Odoribacter laneus has no effect in Sucnr1 knock-out mice. Weight evolution (a), food intake (b), and fasted serum succinate levels (c) of C57BL/6 wild type (WT) and Sucnr1 knock-out (KO) mice treated with O. laneus. Glucose (d) and insulin (e) tolerance tests of WT and Sucnr1 KO mice before and after probiotic treatment. mRNA expression levels of inflammatory genes in the scWAT, vWAT, liver, and intestine (f) (n = 7–8). Data are presented as mean + s.e.m. *p < 0.05; (unpaired t-test and two-way ANOVA)

Fig. 6

Plasma and fecal succinate levels and presence of Odoribacteraceae in a cohort of morbidly obese patients in association with anthropometric and metabolic parameters. Kendall’s tau_b correlation coefficients between plasma (a) or fecal (b) succinate and different metabolic and anthropometric parameters. Correlation heatmap of host metabolic parameters and clr-transformed Odoribacteraceae species (c) (n = 25). *p < 0.05; **p < 0.01

Fig. 7

Plasma and fecal succinate linked to metagenomic functions. Dotplot (a) and Manhattan-like plot (b) showing the significantly expressed KEGG metagenome functions associated with plasma succinate. Dotplot (c) and Manhattan-like plot (d) showing the significantly expressed KEGG metagenome functions associated with fecal succinate