A purified membrane protein from Akkermansia muciniphila or the pasteurized bacterium improves metabolism in obese and diabetic mice

Abstract

Obesity and type 2 diabetes are associated with low-grade inflammation and specific 34 changes in gut microbiota composition [1][2][3][4][5][6][7] . We previously demonstrated that administration 35 of Akkermansia muciniphila prevents the development of obesity and associated 36 complications 8 . However, its mechanisms of action remain unclear, whilst the sensitivity of 37 A. muciniphila to oxygen and the presence of animal-derived compounds in its growth 38 medium currently limit the development of translational approaches for human medicine 9 . 39Here we addressed these issues by showing that A. muciniphila retains its efficacy when Akkermansia muciniphila is one of the most abundant members of the human gut 53 microbiota, representing between 1 and 5% of our intestinal microbes 10,11 to improve glucose intolerance and insulin resistance regardless of the growth medium used and 71 independently of food intake ( Fig. 1a-g). 72 We previously showed that autoclaving A. muciniphila abolished its beneficial effects 8 . (Fig. 1a-c and Supplemental Fig. 1a-c). In both sets of 81 experiments, we found that mice treated with pasteurized A. muciniphila displayed a much lower 82 glucose intolerance and insulin concentration when compared to the HFD group, resulting in a 83 lower insulin resistance (IR) index (Fig. 1d-g and Supplemental Fig. 1d-g). Treatment with 84 pasteurized A. muciniphila also led to greater goblet cell density in the ileum when compared to 85 ND-fed mice (Fig. 1h), suggesting a higher mucus production, while normalizing the mean 86 adipocyte diameter (Fig. 2a-b) and significantly lowering plasma leptin when compared to HFD-87 fed mice (Fig. 2c). These effects were not observed in mice treated with live A. muciniphila. A 88 similar trend could be observed for plasma resistin (Supplemental Fig. 1h), thereby suggesting 89 improved insulin sensitivity, while plasma adiponectin remained unaffected in all conditions 90 (Supplemental Fig. 1i). We found that mice treated with pasteurized A. muciniphila had a higher 91 fecal caloric content when compared to all other groups (Fig. 2d), suggesting a lower energy (Fig. 2e-g). This resulted in a normalization of the HFD-induced shift of 37% with the 104 pasteurized bacterium, and 17% with the live bacterium ( Fig. 2f). 105By comparing the metabolic profiles of the different groups, we found that the shift 106 induced by pasteurized A. muciniphila was mainly associated with trimethylamine (TMA) and TMA to TMAO, a metabolite associated with atherosclerosis 19,20 . While exposure to a HFD led 114 to a two-fold higher Fmo3 expression when compared to ND-fed mice, treatment with 115 pasteurized A. muciniphila reversed this effect (Fig. 2j) Fmo3 expression were not associated with a modification of plasma TMA and TMAO, as all 121 HFD-fed group displayed similar concentrations for both metabolites (Fig. 2k,l) (Fig. 3a), but not cells expressing TLR5, TLR9 or the NOD2 receptor (Fig. 3b-131 d). 132Genomic and proteomic analyses of A. muciniphila identified p...

Metabolic characterization and viable delivery of Akkermansia muciniphila for its future application

“…This alternative annotation is also reflected in Table 4 and a previous proteomics study, where the protein encoded by this gene was located on the outer membrane (Ottman, et al, 2017). The gene upstream of this putative ftsA/pilM gene, is the gene coding for a hypothetical protein on locus Amuc_1100, and its product was found to be involved in host signalling (Plovier, et al, 2017). We found no significant differences in the expression profiles of this gene.…”

“…It was shown in mouse models that changes or interventions in the microbial composition may have influences on host metabolism and psychology (Dinan, et al, 2013, Plovier, et al, 2017). In addition, alterations and interventions in the gut ecosystem may cause diseases, as was discovered in the Nobel Prize winning case of Helicobacter pylori, which can cause ulcerative colitis (Marshall andWarren, 1984, Ahmed, 2005).…”

“…In follow-up studies it was shown that the same or an even stronger effect can be achieved by pasteurizing the cells before administration. Finally, a purified outer membrane protein was administered to the mice that mimicked the effect of a whole cell supplement (Plovier, et al, 2017). Additionally, it was shown in vitro that an A. muciniphila outer membrane complex could modulate the immune response.…”

“…muciniphila by gavage was found to protect mice from diet-induced obesity (Everard, et al, 2013, Plovier, et al, 2016. Moreover, A. muciniphila was found to be safe for use in humans (Plovier, et al, 2016).…”

“…Moreover, A. muciniphila was found to be safe for use in humans (Plovier, et al, 2016). Incorporating this functional microbe in food products or medicine could be the starting point for obesity and type 2 diabetes prevention; however, the application of A. muciniphila may be challenged by its sensitivity to low pH, shear, and oxygen .…”