Foodborne Carbon Dot Exposure Induces Insulin Resistance through Gut Microbiota Dysbiosis and Damaged Intestinal Mucus Layer

Abstract

Foodborne carbon dots (CDs), an emerging food nanocontaminant, are an increasing risk factor for metabolic toxicity in mammals. Here, we report that chronic CD exposure induced glucose metabolism disorders via disruption of the gut−liver axis in mice. 16s rRNA analysis demonstrated that CD exposure decreased the abundance of beneficial bacteria (Bacteroides, Coprococcus, and S24-7) and increased the abundance of harmful bacteria (Proteobacteria, Oscillospira, Desulfovibrionaceae, and Ruminococcaceae), as well as increased the Firmicutes/Bacteroidetes ratio. Mechanistically, the increased pro-inflammatory bacteria release the endotoxin lipopolysaccharide, which induces an intestinal inflammation and disruption of the intestinal mucus layer, activating systemic inflammation and inducing hepatic insulin resistance in mice via the TLR4/NFκB/MAPK signaling pathway. Furthermore, these changes were almost completely reversed by probiotics. Fecal microbiota transplantation from CD-exposed mice induced glucose intolerance, damaged liver function, intestinal mucus layer injury, hepatic inflammation, and insulin resistance in the recipient mice. However, microbiota-depleted mice exposed to CDs had normal levels of these biomarkers consistent with microbiota-depleted control mice, which revealed that gut microbiota dysbiosis contributes to CDinduced inflammation-mediated insulin resistance. Together, our findings revealed that gut microbiota dysbiosis contributes to CD-induced inflammation-mediated insulin resistance and attempted to elucidate the specific underlying mechanism. Furthermore, we emphasized the importance of assessing the hazards associated with foodborne CDs.

Impact of Whey Protein Corona Formation around TiO2 Nanoparticles on Their Physiochemical Properties and Gastrointestinal Fate

“…Compared with the control and TiO 2 nanoparticle groups, the proportion of Firmicutes and Bacteroidetes increased in the whey protein and whey protein-coated nanoparticle groups, especially in the whey protein group. Previous studies have reported that a decrease in the ratio of Firmicutes to Bacteroidetes (F/B) is associated with a decrease in energy intake, so the addition of whey protein may increase energy intake in the body. , Previous studies have also reported that an increased F/B ratio is associated with metabolic syndrome, which is a sign of gut microbiota associated with diet-induced obesity, hyperglycemia, and other metabolic disorders …”

“…Compared to the control group, the TiO 2 nanoparticles increased the proportion of harmful bacteria ( Klebsiella ) and decreased the proportion of beneficial bacteria ( Collinsella ). In contrast, the free and adsorbed whey protein had the opposite effect, suggesting that whey protein could regulate the composition of the gut microbiota, increasing the number of beneficial bacteria and reducing the number of harmful bacteria . In addition, compared to the uncoated nanoparticle group, the proportion of Bacteroides in the coated nanoparticle group increased after fermentation for 24 h. Studies have shown that Bacteroides mainly participate in the degradation of carbohydrates, produce short-chain fatty acids, provide nutrients and energy for the body, and play an important role in improving the metabolism and immune disorders of obese individuals. , It should be noted that it is usually too simplistic to divide gut bacteria into “beneficial” and “harmful” groups, as this depends on the context, such as the health of the person.…”

Long-term exposure to polystyrene microplastics promotes HFD-induced obesity in mice through exacerbating microbiota dysbiosis

“…Mice were administered a mixture of antibiotics (vancomycin [0.5 g/L], neomycin sulfate [0.5 g/L], metronidazole [1 g/L], and ampicillin [1 g/L]; Sigma-Aldrich) in their drinking water for 5 consecutive days prior to FMT. Fecal transplant was conducted according to established protocols [40][41][42]. Brie y, 8-weekold male donor mice were fed either HFD or HFD + PS, while recipient mice were fed microbiota derived from either HFD or HFD + PS.…”

Foodborne Carbon Dots Aggravate High-Fat-Diet-Induced Glucose Homeostasis Imbalance by Disrupting the Gut-Liver Axis

“…Furthermore, nano TiO 2 additive in food worsens the effects of HFDs on the gut–liver axis and related metabolic diseases by damaging the intestinal mucus layer and causing gut microbiota dysbiosis . Since foodborne CDs also have a small size and can easily enter cells, they may also adversely affect intestinal function and hepatic glucose metabolism in individuals susceptible to metabolic diseases. , Therefore, exploring the effects of food-borne CDs and CDs combined with an HFD on the gut microbiota and gut–liver axis may alert the public to the potential harm of foodborne CD intake and provide theoretical guidance for the treatment of related diseases.…”