Common food additive alters gut microbiota in mice

A common food additive, recently banned in France but allowed in the U.S. and many other countries, was found to significantly alter gut microbiota in mice, causing inflammation in the colon and changes in protein expression in the liver, according to research led by a University of Massachusetts Amherst food scientist.

Along with colleagues at UMass Amherst and in China, Xiao published the research in Small, a weekly, peer-reviewed, interdisciplinary journal that covers nanotechnology.

Gut microbiota, which refers to the diverse and complex community of microorganisms in the gut, plays a vital role in human health. An imbalance of gut microbiota has been associated with a range of health issues, including inflammatory bowel disease, obesity and cardiovascular disease.

Human exposure to foodborne TiO2 NPs comes primarily from a food additive known as E171, which is made up of different-size particles of TiO2, including one-third or more that are nanoscale. E171, which makes products look whiter and more opaque, is found in such food as desserts, candy, beverages and gum. E171 exposure is two to four times higher in U.S. children than in adults, Xiao points out that one study found.

Smaller than 100 nanometers, foodborne nanoscale particles may have unique physiological properties that cause concern. "The bigger particles won't be absorbed easily, but the smaller ones could get into the tissues and accumulate somewhere," Xiao says.

In their study, Xiao and his team fed either E171 or TiO2 NPs to two populations of mice as part of their daily diet. One population was fed a high-fat diet similar to that of many Americans, two-thirds of whom are obese or overweight; the other group of mice was fed a low-fat diet. The mice fed a high-fat diet eventually became obese, while the mice on the low-fat diet did not.

The researchers found TiO2 NPs decreased cecal levels of short-chain fatty acids, which are essential for colon health, and increased pro-inflammatory immune cells and cytokines in the colon, indicating an inflammatory state.

To evaluate the direct health impact of gut microbiota disrupted by TiO2 NP, Xiao and colleagues conducted a fecal transplant study. They gave mice antibiotics to clear out their original gut microbiota and then transplanted fecal bacteria from the TiO2 NP-treated mice to the antibiotic-treated mice. "The results support our hypothesis that including TiO2 NPs in the diet disrupts the homeostasis of the gut microbiota," Xiao says, "which in turn leads to colonic inflammation in the mice."

The study also measured levels of TiO2 in human stool samples, finding a wide range. Xiao says further research is needed to determine the health effects of long-term - such as life-long and multigenerational - exposure to TiO2 NPs.

БИЛЕТ 10

1. Can Antibiotics Increase the Risk of Arthritis? By Ratan-NM

Rheumatoid arthritis (RA) is an autoimmune disorder that causes inflammation of the joints. RA is a chronic and progressive condition that causes debilitating effects on the patient. The condition is characterized by pain and stiff joints.

Another typical feature of this disorder is bone and joint destruction and the presence of autoantibodies in the serum and synovial fluid. Synovial fluid is the fluid that lubricates the synovial joints.

What causes rheumatoid arthritis?

The exact mechanism by which patients develop RA is unknown; however, a combination of genetic and environmental factors is likely. Autoimmune antibody production is proposed to be the main mechanism responsible for bone and joint destruction, and the related RA pathology. Infections, hormonal alterations, and stress are some potential triggers of RA.

Recent research suggests an association between antibiotic use, gut microbiota changes, and RA flares.

Antibiotics and the gut microbiota

Antibiotics are widely used for the treatment of bacterial infections associated with the respiratory system, gastrointestinal system, and urinary tract. Although antibiotics act against pathogenic bacteria, they can also modify the normal gut microbiota.

The gut microbiota is a diverse system of microorganisms residing in the gastrointestinal tract of the human body. Gut microbiota plays a vital role in maintaining the body’s digestive health. Gut microbiota is also involved in the immune system and the synthesis of vitamin B and vitamin K.

Various epidemiological studies have demonstrated associations between the occurrence of bacterial infections and RA. Furthermore, microbiome alterations have been indicated as a potential mechanism for the effect of infection in RA pathogenesis. Antibiotics substantially disturb the gut microbiome, with studies demonstrating significant microbial shifts in the gastrointestinal tract following their use.

The alterations in the gut microbiome may last up to a year after treatment periods of only one week. As per a recent study by Nagra et al., the risk of RA flare was significantly increased in the 1–12 months after commencing treatment on sulphonamide and trimethoprim antibiotics.

Antibiotic usage and the risk of rheumatoid arthritis

Emerging research suggests that infections are potential risk factors for RA pathogenesis and flares. Respiratory infections have been particularly linked with the development of RA. Antibodies to citrullinated peptide antigens (ACPA) are one of the autoantibodies associated with RA.

ACPAs have been found to be produced in response to certain bacterial components, which suggests the potential role of infections in RA pathogenesis.